I's say Moonbeams Wold Top Festival without a doubt. The most beautiful setting imaginable high up on the lovely Yorkshire Wolds, on a farm with its own brewery. Superbly organised, with excellent artistes (Oysterband headlining this year) and the best singaround tent ever. It's on 8/9 July so you'll have to get your skates on.

Details here:
Moonbeams

Can't wait! See you there!