Carbs are generally more important than protein, for recovery purposes after a hard ride. It's important to eat both though. Try to eat something with a 4:1 ratio of carbs to protein.
I usually just drink water on rides, and get my calories from food. I prefer it that way, both for taste and i feel my body works better like that. I have used accelerade though, that stuff is good.
Whey protein from a mix is probabley just as good as any, it might get absorbed even faster, i like eating whole foods better though.