I'd vote for Gen 2! I'm biased though :P
Seriously, If you can put gen 1 headlamps with gen 2.5 grille and bumpers, and gen 2.5 tails, it would rock :)
Somehow i like the headlamps on the Gen 1.
On gen3, if it's not because of the higher headlights, if i glanced at it from the front, it would look a lot like 2003 camry, rear side is totally different though.