Hey Descydia,
first, what do you mean by rig? do you mean tank or reg (regulator)? if you are looking for a tank, manufacture does play a big role. some of what mendo7 said was correct. there are a few things that separate a good tank from a bad tank. stick with a company that sells replacement parts. Pure Energy (Empire) sells rebuild kits for the tank regulators and ALL of the other replacement parts such as the gauge, fill nipple, burst disks, and bonnet (threads). a lot of these parts are interchangeable with other brands like crossfire, CP, ninja etc...
We carry mostly Pure Energy tanks because the parts are inexpensive and readily available. The reg performance is excellent and we never have any complaints. (I use one myself and so does the rest of the team). CP and Crossfire tanks are excellent also, but they are anywhere from $20-$70 more than Pure Energy. We can always order you ANYTHING you want if we do not have it in stock. (just because you dont see it, doesnt mean we cant get it)
Other companies like Ninja, Guerrilla, Myth, we do not carry because if the regulator needs to be rebuilt or fixed...they need to be sent back to the manufacture for repair. Also the performance of the regulators is not great at all. some regs will "choke" or starve the gun for air causing shoot-down problems.
Let me know what kind of marker you have and i can steer you in the right direction. A lot of it is between personal preference and how much you want to spend. the steel tanks are heavier and hold 3000 psi but are less expensive. the carbon fiber tanks are significantly lighter and usually hold up to 4500psi but 2x-3x the price of the steel tanks.
OR you can just drop by the store, talk to me (Justin) or John and check out what we have in stock and you can make a decision from there.
Any other questions just let me know. Thanks.