I would say Crete but it can be windy. My vote is kefalonia.

Santorini in July is going to be crazy busy with tourists. There is a cute area next to Gavalas Winery. Off the beaten path with lots of character and Tavernas. Also a swanky resort by Marriot there that is completely hidden. Go check out Raki Bar. I’ll likely never go to Santorini again and stick to Kefolonia!

Check out Iliana Malihin Winery if you can!