We might as well follow the colour wheel so let's kick things off with white.
Both are very good, depending on which way your deck leans.
Without a doubt the two best commons are Waxmane Baku and Split-Tail Miko. You'll be very happy to get either of these two with your first pick most of the time. Split-Tail Miko often doesn't come online until turn five or six as you will usually be tapping out for creatures in the first few turns of the game but once he does come online he's very powerful. Having a mana cost attached to its ability is annoying but more than acceptable as the ability is just so good. The Baku would still be my choice over the Miko in any sort of spirit/arcane focussed deck and especially an aggressive one which primarily featured ground-based attackers. The flexibility of the Baku is what makes it so good; you can tap one guy down for several turns or tap down a series of blockers for just one mana, allowing you that finishing alpha-strike.
Coming in a way behind those two but still being very playable is Moonlit Strider. This guy has been very good for me so far as he's a fine blocker in his own right and has two useful abilities attached. There are numerous situations you can get in where your opponent can't really avoid giving you two-for-one as the Strider saves a creature and returns another via Soulshift.
Kami of False Hope and Kami of Tattered Shoji round out the decent playable creatures amongst the commons. Both of these are fine cards, and are obviously best in a Spirit-themed deck. Takeno's Cavalry is terrible and I've found Silverstorm Samurai to be very unimpressive so far. This is a much faster format than previous ones and a white Tangle Spider that doesn't even block flyers just doesn't do it for me I'm afraid. Samurai Enforcers would be better most of the time and that isn't a great card in the first place.
Mending Hands and Hundred-Talon Strike are the best of the common spells that are available to you. If Mending Hands was Arcane it would definitely be my favourite of the two simply because it's a little more flexible. It can save a creature or throw off an opponent's combat math allowing you to win a close race. As it is though, the Arcane nature of Hundred-Talon Strike makes them about equal overall. Strike is better in an aggressive deck as you'll be attacking more and being able to take out blockers cheaply is just what you need.
Heart of Light is a very bad version of Cage of Hands because when used on an opponent's creature it creates a fantastic blocker for them. However it does deal with cards like Frostwielder and it's a fantastic sideboard card against red-green where you can put it on your own creatures without risk of them getting bounced or destroyed. If you have a deck that plans on winning with flyers anyway then a bad Cage of Hands is probably better than no Cage of Hands at all. Note also that this is very nice with Tallowisp for obvious reasons.
Faithful Squire, Genju of the Fields and Terashi's Verdict are the standout cards amongst the uncommons. I think I'd take all three of these over any of the commons except possibly Waxmane Baku if my deck was able to use that card to its fullest. The Squire is very good indeed and it's pretty easy to flip it. When you do so, it's very hard for your opponent to race a three-power flyer whilst getting around the damage prevention effect at the same time.
Overall white has something for everyone. The defensive blue-white decks gain Split-Tail Miko and Moonlit Strider and the more aggressive decks will benefit more from Waxmane Baku and Hundred-Talon Strike. There's a lot to like in white as both the Baku and Split-Tail Miko would make my top five commons from the set.
A close one, but the ninja wins out.
Moving around the colour wheel one notch brings us to blue.
Ninja of the Deep Hours gets my pick for best blue common followed fairly closely by Shimmering Glasskite. The ninja has proved its worth to me numerous times as you're almost always able to get at least one hit off it in the early game. When you can't get through or you're in a position where you don't want to lose the tempo you can just hard cast it as a four mana 2/2 whose presence might cause your opponent to rethink his attacking options. There are lots of cards that can force the ninja through for extra damage such as Kami of the Waning Moon or Phantom Wings and spells like Toils of Night and Day. You recoup any lost card advantage as soon as the ninja hits.
Shimmering Glasskite is a solid flyer and has a useful ability attached. Sometimes though the ability isn't always beneficial as there might be games where you have to pay an equip cost twice or where you can't prevent combat damage to it or can't use an Indomitable Will or the like to save it. In addition to that your opponent can always target it with a free effect from a Split-Tail Miko or Frostwielder or similar, let that effect be countered, and then use their removal spell on it. Overall it's a solid flyer, but not spectacular.
There are a lot of fairly mediocre cards filling out the rest of the commons. Cards like Teardrop Kami, Mistblade Shinobi, Veil of Secrecy and so on aren't exciting but aren't unplayable either. There's a reasonable amount of depth here but there's nothing else that really makes you want to draft blue. I don't like Minamo's Meddling in the main deck as it seems a little too expensive, and Phantom Wings won't always be playable either. If you need a slow bounce spell or have creatures that benefit from the evasion then it's fine, but otherwise I'd generally leave it out if I could.
Things pick up slightly in the uncommons. Genju of the Falls is the best of the bunch but Jetting Glasskite is also very nice. Callow Jushi is solid and can become very good in the right deck, and Kaijin of the Vanishing Touch is a good addition to any deck that requires an early ground defence. Soratami Mindsweeper is fine too and can provide an alternative win condition albeit a fairly slow one. In an average game you'll need to mill someone for around 22-24 cards which means 22-24 mana spent on it's ability and 11-12 lands returned to your hand over the course of the game. It can be done but I wouldn't want to rely on it really.
There's a fair amount of unplayable stuff here too though. Quash is too situational really unless you're in desperate need of something to sideboard in against that triple Glacial Ray deck. Stream of Consciousness does nothing, as does Heed the Mists but at least that only does nothing about half the time. Walker of Secret Ways I don't anticipate making the cut in any of my decks either. Its ability isn't awful by any means but it requires two mana to use, and it can only be used in your turn and it's attached to a pretty weak three mana 1/2 creature. Occasionally you might be able to attack your Ninja of the Deep Hours into an opposing 2/2 with this in play but even then your opponent might just block anyway which means the ninja is back in your hand and you've spent 7 mana on the Walker of Secret Ways + its ability and lost a lot of tempo at the same time. Even when it works this ability might be bad for you.
Overall there's not a whole lot to love about blue. Certainly there's nothing here that really steps up to replace the top blue commons from Champions like Teller of Tales, Soratami Rainshaper, Consuming Vortex and Soratami Mirror-Guard.
Not just the best common in black, it's the best common in the set.
Now we move into the darker side of Magic as we look at the second of the two colours to feature the ninjutsu mechanic.
The best black common by far is Horobi's Whisper. It's better than all of the common black removal spells in Champions and for me it's the best common in the set. Its casting cost is cheap, it's instant and it's Arcane. It's got a Splice cost that's very manageable, especially in games that go long. Indeed the ‘free' Splice cost means you're able to splice this onto other more expensive Arcane cards that you might not otherwise be able to use as a Splice vehicle. Although it does have double black mana in its casting cost you can Splice it with just a single Swamp but that still doesn't really make it splashable.
Second place is a close-fought battle between Takenuma Bleeder and Okiba-Gang Shinobi. Getting an easy to cast 3/3 monster on turn three is very good in this format and the drawback is a very minor one. Unlike Scourge of Numai and older cards like Fledgling Djinn the Bleeder won't continue to damage you if it gets shut down by a wall or nullified by something like Cage of Hands or Mystic Restraints. It's definitely the best common three-drop black has. The Shinobi is has a much more powerful effect but you sacrifice a lot of tempo to achieve it. If you spend your fourth turn returning your third turn play via ninjutsu and your opponent can deal with the Shinobi cheaply before it hits them your board might look rather empty. Despite that, snatching two cards from an opponent's hand early in the game is very powerful and there's always the threat that you'll take two more the turn after as well. It's very difficult for most decks to recover from the loss of four cards early in a game and I'd probably give the nod to the Shinobi over the Bleeder in most decks for that reason.
Beyond those three cards things go downhill fast. There's a lot of stuff that's playable, like Stir the Grave and Skullsnatcher, but both of those cards are pretty mediocre really. Stir is quite expensive and at Sorcery speed gives few opportunities for any nice tricks. Skullsnatcher is a second turn 2/1 which is fine but it isn't as good as Cruel Deceiver or Wicked Akuba.
I've played with both Skullmane Baku and Call for Blood and neither have ever impressed me significantly. Call for Blood is very situational and often requires you to sacrifice a useful creature to take down the target you want Yes you can use it when damage is on the stack or in response to a removal spell to sacrifice a creature that was basically dead anyway but even when you do that you aren't gaining any sort of advantage really, it's just a simple 2-for-2 trade and for five mana you'd really expect something better than that. I'm tending to leave Call for Blood in my sideboard these days. Skullmane Baku often joins it there as it's terrible as a five mana 2/1 and you really need a lot of Spirits and Arcane cards in your deck to still have a handful beyond the fifth turn.
The rest of the commons I wouldn't normally be thrilled about playing main deck but many of them have their place in certain match-ups. Blessing of Leeches can be good sometimes and horrible in other situations where your opponent is able to nullify the enchanted creature and you're forced to watch your life points slowly drain away. Psychic Spear is a weak 23rd card but an excellent sideboard card and one that will really hurt some decks, including the Dampen Thought archetype, although I don't really see that surviving through this set.
Picking the best of the uncommons is a difficult task, and unusually I think the Genju doesn't make the top three. Hired Muscle continues the theme of excellent flip cards and both Eradicate and Throat Slitter are very good as well. All of those cards I'd take above Genju of the Fens. Ogre Marauder is another very good, difficult to block attacker. He'll always take down one creature if he's going to be blocked but sometimes your opponent will sacrifice their Floating-Dream Zubera and then you'll be able to take out the River Kaijin they were planning on blocking with before they're even able to do so. In those situations the Ogre can buy a lot of tempo and at other times he'll still require your opponent to hold back two creatures if they do want to be able to block him.
That's the first three colours dealt with. Next week I'll be summing up the rest of the set as well as kicking off some drafting practice, so I hope to see you then!