The best berries for Pokeblocks are: Ganlon, Salac, Petaya, Apicot and Liechi.

Here is a short list how many contest stat points a Pokemon will get eating a Pokeblock made (in Lilycove) with one of the above berries:

Code:
      Ganlon  Salac   Petaya  Apicot  Liechi

Cool     0      10      49       0      61
Beauty  61       0      10      49       0
Cute     0      61       0      10      48
Smart   49       0      61       0       0
Tough   10      49       0      61       0
All Pokeblocks were level 61 feel 34.