I suppose Planet Hulk could work. I'm not exactly against it, but I'm not for it either. Ultimately it's up to Marvel, and I'll trust whatever decision they make for Hulk. And really, I'd just be happy to have another Hulk movie.
But my ideal vision for a Hulk movie has Bruce Banner up against an invigorated, expanding AIM, either directly lead by the Leader, or manipulated in the background by the Leader. However, Leader wouldn't be the main bad guy just yet.
Instead, I think the U-Foes could make for very very interesting (albeit adapted for big screen) opposing force, that should require not only Hulk to be at his strongest, but for Bruce to be at his smartest, to defeat. Simon Utrecht (otherwise known as Vector) would be the active face of AIM at the time, and his ambitions could either usher in a biological threat (putting the good doctor into more of an actual doctor role), or some outstanding, reality breaking device (possibly involving lots of gamma radiation) that he's trying to perfect, but has a good chance of destroying the world. Due to circumstances, or lack of awareness, Bruce and friends are either the only ones trying to stop it, or the only ones capable of stopping it.
Add some exploration of Bruce's past, and the psyche of the Hulk, but not to Ang Lee levels of borderline dementia, and make sure Bruce is always a proactive participant in events, instead of the man on the run that he's always portrayed as, and I think you've got a pretty good foundation for a Hulk movie.
I won't try to specify any plot points or details though, cause that goes a bit too much into "fan fiction" territory.
