I use hard mauri and sometimes hard hercules tips. They are very good at keeping their shape. They do mushroom out with enough use, but once you fix them once, they never mushroom out again.
The worst tips you can use are the ones that come with the shaft. I don't know what kind of tips they use, but doing trick shots, I can tell you from personal experience that they crack quickly, especially with some of the extreme stroke shots that I do. When I order new shafts, I have a few shots that I try with them initially. Mike Massey's circular draw shot, the one pocket 3 rail draw shot from being frozen on the foot rail, and a couple of other stroke shots. Probably 1 out of 3 new tips crack and a little wedge pops out of them after about 5-10 shots. I think this may be due to the tips being dried out from sitting around in the warehouse. Maybe they are just cheap-o tips. In any event, any serious player should replace the tips almost immediately when they get new shafts. I always do this, and then have them cleaned up a couple weeks after to get any mushroom out that may have appeared.
Andy Segal