Now that day 2 has started here in Beijing and players have started drafting, I checked in to see what colors pros thought were the best and what colors were the worst in Shadows over Innistrad draft.
Pro Tour Hall of Famer Kenji Tsumura: I think Green is the strongest. There are a lot of flip cards so you can tell whether the players to your left and right are in your color. The color level is about the same between many of the colors, but Green and Red get an advantage because of the flip cards. I think that Black and Blue are underrated, but blue is probably the worst color—there are only a few good common cards. Stitched Mangler is the best blue common, but everything else is very bad. Also in Blue you can't tell if the other players at the table are in your color because there are no flip cards.
Grand Prix Taipei Champion Huang Hao-Shan: I think Red and Green are about equal to each other, but Blue and White are definitely the worst.
No. 19 Yuuya Watanabe: I think the strongest is Green and the weakest is Black.
Four-time PT Top 8 competitor Lee Shi Tian: Green is certainly the best color; the werewolves are so big. I think Black or Blue are the worst colors. In black, the creature types do not have good enough synergy to build a deck around. They only have Vampires for synergy, but the creatures don't line up right.