New or used? If you're getting one new, I'd suggest getting the Benchmark .45 frame, it is much better than the stock one. Since Blazers specialize in C02, putting a Stabalizer on one wouldn't be a bad idea either. The barrel options are up to you really (spiral venting/porting will quiet it down, and you can choose whatever length too).
I prefer a set up with the female bottom line stabilizer with a ring mount (the block mount is unecessarily large and bulky in appearance and the ring mount works extremely well) on a NW short lazy Z drop-forward and a gas through grip. With this set up I get the best regulator but I don't have to grab hose on my foregrip.
Palmer Blazer, Black
I find it curious that most people are more interested in opinions than facts.