I think in each generation the gameplay style became more respectable. The overall gameflow became more of "respectable RPG", more complex more to choose from, decisions, strategies. That said, I wish they'd also change the damn plot! Each generation was better than the one before it though. in how the gameplay and mechanics work. Pokemon designs? All generations had both good and bad...I mean most people dog on past 251 with "ugh the pokemon started getting silly" my opinion is that some in all generations are more ugly and less usable (but as concepts still strong) I mean, who uses Cloyster or Parasect?
aww it's hard to choose they are all nice in their own way X3 I really should draw pok'emon more often I used to love it a lot and still do..ah well I chose GSC probably because Cyndaquil pops up every where I go in the games (not literally XD like fo ex. PMD my partner always no matter which version I had cept for explorers of the sky...it's riolu there only cause I am Charmander..ironic cause it was my very first starter pok'emon and now I AM a charmander heh.) ah well anyway they are all my favorites but I like GSC a bit more just a tad.
I always get this new feel when I'm playing a Pokemon game, like it's OMG exciting, I know what's coming up but don't at the same time. But this happens EVERY SINGLE TIME I play a new one. So all of them.
Personally I don't like ANY of the new D/P pokemon... Lucario, maybe, but even he doesn't compare to the older ones. D: I like alot of the R/S/E pokemon, and almost all the the GSC, as well as RBY pokemon.
My favourite gen has to be GSC because the battling style was so improved, as well as the pokemon... there are genders and stuff... *shrugs*