Well, I'll name my top three from each gen and then tell you the winner.
Gen.1: Rapidash, Clefable, Pidgeot
Gen.2: Ampharos, Aipom, Heracross
Gen.3: Sceptile, Salamence, Blaziken
Gen.4: Mamoswine, Lucario, Magmortar
Gen.5: Shimama, Emonga, Tabunne
And the winner is....... Sceptile!