Best Cell Phone Company?

Currently I have a 2 year contract with sprint. I have 300 anytime minutes and unlimited nights/weekends and long distance. I ALWAYS go over so instead of my bill being 30-40 its closer to $50-60. Anyway, my plan is   running out soon and I was considering switching to a different plan/company to try to get the most "bang for my buck". I know next to nothing about the different companies so thats where you guys come in...

Which company is generally considered the best price wise/coverage/etc etc? Are their any useful sites out there to help when picking a new cell company? Thanks!