Quickdraw McGraw on 23 May 2008
Big Boss, for pure character development.
We see Big Boss go from a CIA operative, just listening to what he's told, to the leader of one of the biggest mercenary insurrections in the world.
Obviously a lot happened inbetween (Some of which we have yet to see), but it's a pretty dramatic change, and we see him constantly second-guess authority, and to an extent himself, from the events of MGS3 onwards.
Although I may have to reserve judgment until after MGS4, as Solid certainly has been through a lot, and is easily one of the more developed characters in gaming as well.
