I assume the major factor in this is price. So pretty much the only thing anyone can tell you is that you just have to shop around and compare. First i suggest figuring out what mask and gun you want (for reviews check out
www.pbreview.com). Then look around the web and stores in your area. Most package deals will give you the gun, mask, and hopper. Some will also include the air system. Thats the other thing you have to look into, Co2 or nitro. unless you got a good amount to spend, your gonna get Co2 (nitro normally costs about 150-200 in the low end, and ive seen up to 500+ on the high end, ohh and thats in US currency).
A lot of packages on the web dont give you much choice in what mask you get. Or they do but you pay extra. sometimes its cheaper just to get everything seperate. So pretty much all you can do is look around and research.