I had SunCom way back in the day. I only got it because there was a hot chick working there (we eventually dated). I kept SunCom until they (regionally) got "gobbled up" by AT&T.
AT&T Wireless sucked donkey balls, so I switched to T-Mobile. I also did that because there was a hot chick working there (we eventually had sex, not dated).
I really liked T-Mobile's plans (my last one was 1500 minutes, free nights/weekends, unlimited texting for $49.99 a month), but I couldn't get any reception in many of the areas that were supposedly "full coverage" on the map.
Now, I'm with Verizon, which is more expensive, but have had little, if any, reception problems. Only oddity is that in one section of podunk Alabama where I did get reception with T-Mobile (I have to drive through Alabama to get from home in TN to school in FL), I don't get any reception at all with Verizon. It's only a stretch of about 5 miles, but it's still weird.
Anyway, Verizon = Good but expensive.
T-Mobile = Cheap but sucks.
Wireless phone sales girls = hot and fun.