I recently re-plumbed my system and replaced the cheap/troublesome ball valves with Pentair valves. These (and the similar Jandy valves) are actually more of a "cylinder" than a ball valve, and they are repairable as well. This was a HUGE improvement in ease of actuation and highly recommended. I purchased from this e-tailer and received very good prices and service:
http://www.discountpoolzone.com/mult...multiport.html