I have been a long-time sprint customer, and am pretty happy with them, BUT, verizon is releasing the sholes (motorola droid) which looks pretty cool.
The verizon plans are a bit on the high side, but if t-mobile is launching their everything plan for $50
http://forum.ppcgeeks.com/showthread.php?t=89892 , and wal-mart is going to start becoming a provider, I am pretty hesitant to sign anything at the moment. This competition will surely force all the carriers to re-think their prices in our economy.
I am eligible for an upgrade with sprint nov 1st, and just about jumped on the hero bandwagon, but with everything happening in the cellular world, I think waiting a bit to see what happens is the best way to go....just my 2cents.