Steel steel steel. If your range allows it. I hate manually resetting targets. Poking holes in paper has its purpose but low-maintenance reactive targets make a range day more enjoyable.
I make rinfire targets out of 1/4" mild steel, haven't had an issue with shooting 22 at them. Centerfire blows them up, so for that I stick to ar500 and only use beyond 100 yds.
I also keep an eye on cabelas for target sales, I have about 12 of their 3/8" thick torso targets set up. The little resetting gopher poppers are gold, you'll just have to hammer them flat from time to time after a good shooting session.