Apples: Braeburn or Fuji are the only ones I will buy - sweet/tart and firm
Cantalope: Tuscan or French Kiss only
Stone fruits - orchard fresh or from a farmers market, the ones in the stores are gross, mushy and have no taste.
Grapes - grocery store seem to be decent, I like green w/a tinge of yellow, DD likes red seedless and DH likes the really dark ones, all seem to be good.
Watermelon - hit and miss
Strawberries - I go by smell, not looks. They might look tiny and sickly but when they smell great they generally taste great.
Blue & Rasp Berries - US grown only and Pacific NW cranks out some good ones.