I suppose that there's good and bad about all of them. Whatever phone you get will be obsolete or a piece of junk in 6 months.
I stated with AT&T got sold to Cingular. Switched to Verizon because it was suppose to have the best reception all over the US according to Consumer Reports (so much for that!)
As soon as I got Verizon in DFW TX, my reception quality got worse. I had to go outside my old studio to make a call, whereas with Cingular it was fine inside. But in upstate NY, my old AT&T wouldn't work at all.
What works in one place may not work in another. If you travel, this may be a consideration. Maybe Verizon is just no good in DFW TX.
I think they're all hit or miss or blue sky.
With cell phone companies it isn't the one you like the most, it's the one you hate the least.