The one climb that made me really happy at Hueco was Nobody Gets out of Here Alive (V2?). I suck at overhangs. I was really excited when I got this. The thoughts of Lobster Claw (V5) out there still haunts my dreams.
Locally at the Niagara Glen one of my favorites that I'll do again and again is God Must be a Climber (V3), the other that I was working on the last couple of times I was down there is Backstroke (V4/V5??). Both are traversing problems with fun footwork and heel hooks.