Flexi ION, new 2008 waroo are two nice ones I've ridden and liked how they felt unhooked.

I learned to ride unhooked on my 06 waroos (probably one of the worst kites for freestyle).. I wouldn't consider it a "good" kite for unhooking but the large depower range made it easy to get hooked back in without loosing too much ground.

I think it's more about the rider than the kite when riding unhooked, but I know Scott will argue with me on that.