I can only pick one? If I had to choose an overall favorite, I'd say cherries, with strawberries a very close second. When I was a kid my mom experimented with growing fruit. First it was grapes, then she gave up on those and got apple trees and made a strawberry patch. I loved going out to the backyard and picking ripe strawberries.
I really liked ground-cherries, though I haven't met many people who know what they are. I haven't met many fruits I didn't like. I don't like avocados, grapefruit, or acai berries.