Seriously, don't get C02. Most of them are of lower quality and will break a lot faster. When a seal goes on a C02 pistol it's cheaper to buy a new gun than find and buy parts.
My suggestion? Get one of the new WE pistols. They make a few Glock models, the Sig Sauer 226, M&P pistols, and a handful of others. I own the Glock 17, Glock 18c, Sig 226 and I'm probably getting the M&P.