I have over 3000 eevee candy, because the town i lived in up till late late last year constantly spawned eevees. Also a fair amount of machops spawned there. This town was a weird place for catching pokemon, not many pokemon spawned there but sometimes it would throw out rare spawns like Dragonite, Togepic and Aerodactyl. Caught several Snorlaxes there, never seen a single wild Snorlax anywhere else. But for sheer grinding it was a poor town.
Also have 2000 Magikarp candy and have evolved about 12 gyarados' in my time. This is because when the game first came out i used to go to a water biome everyday and caught about 30 Magikarps daily.
I don't evolve much except powerful mons so i have thousands of candy for various pokemon.