For starters, I'm a massive Bendis fan. I started reading Avengers after disassembled (and I suspect that's the case with many readers because that book and Dark Avengers were massive sellers for a very, very long time) and I actually got back into Marvel comics with his work alongside the likes of Millar, Brubaker, Morrison and JMS (on Supreme Power, I disliked JMS on Spider-man).
Without doubt, Bendis shaped modern Marvel and influenced the larger industry as a whole with his "de-compressed" story telling which has pretty much become a staple of superhero comics today. The impact of Bendis leaving Marvel can't be understated because this means the biggest name draw writers and artists in comics today are at DC (Snyder and Johns are guys that can pull sales on name recognition alone and artists like Finch, Daniels, Lee, Hitch can move sales). In recent times though, Bendis seemed to be experiencing some creative burn out and he doesn't have the spark he used to have. His recent Marvel work hasn't been like his earlier work and a lot of it has been pretty "slow". His moving to DC is probably best for him as it presents a new challenge.
However, this kind of leaves a vacuum at Marvel and I'm curious who you guys would like to see be an "architect" at Marvel. Bendis wasn't yet a big name writer when he started his amazing run on Daredevil before Avengers and i would love to see Marvel give another writer a big push. Right now, it seems Jason Aaron is playing that architect role (but I strongly suspect that Aaron will jump ship to DC sometime in the future because he's always stated he's a life long DC fan and he actually got his break there). Personally, I would love to see Saladin Ahmed get a high profile book at Marvel. Black Bolt has been amazing and is Marvel's best book at the moment. Another guy I would love to see get a higher profile is Charles Soule, his work thus far has largely been excellent (although Astonishing X-men is slowing down) and he's a guy that could do some amazing work on an Avengers title.