brandon, the first question you should ask yourself is:
"what do i need a valve for?"
gate valves and ball valves have there strengths and are better suited for some jobs than the other.
gate valves are excellent for making minor adjustments in flow, allowing you greater control than a ball valve.
however, if you need a valve to give you on/off control of flow, nothing beats a ball valve. with just a half turn your line is either open or closed. try that with a gate valve, youll be standing there for a minute or so turning that valve till you get it completely shut or open. which isnt the most comfortable option when dealing with plumbing that is either behind and or under a fish tank.
so, figure out what type of control you need and go with the "better" valve for that purpose.
