My best places used so far:
1: Circular Quay in Australia (-33.8599139,151.2121163), Best for Water pokemons, in 3 days i looted 800+ magikarp candies and 125+ squirtle candies (could be even more, but i was using pokefarmer only 6-8 hours per day)
2: Rice Park in Minnesota (44.944662,-93.0970992), According to reddit is very good place for rare pokemon. Personally i didnt catch so much super rare pokemons, but this place good enough for grass pokemons.
3: 6 pokestops in 1 place in Minnesota (45.030060 -93.319229), This place is not so good actually, but it always lured and i found hundreds eevee there. So if you looking for place to farm eevee candies for good vaporeon you can go there.