I happen to have a G21 and a G30. I will say that the G30 seems to be about as accurate as the G21, and both are probably better than I am. With 10 round magazines, you can get all your fingers on the G30 grip, so it's basically very similar to shooting the G21. I'd pick the one you like, hard to go wrong with either one. FWIW, I don't own any G21 10 round magazines, and since I had such lousy luck with the G17 10 round magazines, I never will own any of them!