Towel is the best. played with a towel for some time, and got shot on the breakout... about 5 times in the towel. i didn't feel it, just absorbs the impact pretty well. Now the towels are banned where i play, because they promote bounce, so everybody are using cups. some people prefer to find some good bold pieces of rubber and put them in the pants instead of the soft stuff that is there, and that too works fine. So better use a towel, but if it's banned, a cup will do best in my opinion, or a tougher insert in the pants.