For me, in semi-arid zone 7b, the most consistently drought tolerant tasty fruit trees seem to be:
Apples.
Peaches / plums / apricots / cherries / chokeberries / most stonefruits in general.
Hackberry.
Clove currant.
Thornless blackberries and raspberries.
And I'm going to add carob to the list, because even though it's a zone 9 plant and I have to grow it in a greenhouse, it's so awesomely drought tolerant that I've gotta love it.
Also, are you only looking for fruit trees? I could talk about annuals and perennial vegetables that are tasty and great in my climate, as well.
I'd definitely add wine cap mushrooms to the list, even though they're not a plant, because they're edible and make everything else grow better.