Finding a Good Gun:
Most people don't fight well with a gun they don't like or can't use very well. Some people like Medium Cannons and Heavy Caliber Water-cannons, like the 1700, 2000,2500,2700etc. While others fight Good with medium to Small Assault Water rifles such as the 150, Md600, 5000, 310 etc. Some are better off with no gun at all and just use waterballons .
Aside from these facts, you need to find a gun that you like better than all the Others or maybe you're the type to use no gun. Here is something that should help you narrow down what you need or want.
Using this list you should be able to decide on a particular water-gun that will meet your needs and one you'lle love