I tried CM9 for a day, Trebuchet and Apex are very similar IMO. Maybe a different
features here and there but they look and feel pretty much the same.
They are both based on the stock launcher, just with custom features. Nova Launcher is the same, but I think the dev wrote it from scratch.
Trebuchet is probably from scratch too since it is from CM.
If you want to keep a stock launcher look and feel, Nova, Trebuchet, and Apex are your best bets. I consider ADW purely for customization and only use it when I want to make a fancy homescreen. If ADW had the same widgets picker as the others, it would be my daily. Also, out of the 3 ICS launchers, I think Nova is the only one that supports gestures.