I voted "gen 1" but technically it's gen 3 which had the great gen 1 remakes, on top of everything else.
But gen 1 had my overall favorite roster of Pokemon.
Gen 4 was when the gameplay started to get slower, etc, and the amount of lag in HGSS was insane.
Everybody's got a price / Everybody's got to pay / Because the Million Drachma Man / Always gets his way. AhahahahMMH