That is a hard decision, but either apricots or cherries.
They are all really yummy, though I find if i buy cheaper ones, they often have little taste.
I buy from a specialist fruit/vegetable shop where you can taste most of the goods before you buy them, and that way if they are not sweet enough, or whatever, I move to the next one.
This shop's fruit also lasts far longer than most other shops however, and it is a big however, it costs sometimes almost double other shops.
It is worth it to me as I go once a week and know that it will last.