Flyboy named a great one. I was going to say Sportster also.

I just built a CG Chipmunk last year. Its very crisp and tight. Very precise airplane. I haven't flat spun it. But with that rounded upper deck on the nose, it should flat spin very well. And it is very easy to build. It did take me a little while to get the incedence set up properly and get the planed tuned the way I like it. But its just great now. It knife edges effortlessly. You can fly it with high power, fast and big manuevers. Or you can fly it very slow, the conservation of momentum pendulum thing, at idle most of the time. It seems very versatile.