Verizon's better, but more expensive and not unlimited. If you're fine with that, then by all means, go for it.
Personally, I prefer Sprint, they're good enough for what I do (Pandora streaming in the car), and emails/text. They're also very good when it comes to reception. I just think once LTE hits the area, it's going to be awesome. Not to mention that LTE 800mhz frequency will be released soon after 1900 launches. It's just going to take time and 1900 is the same coverage in terms of distance and building penetration as the 3G. No matter what, 4G LTE 1900mhz is much better than WiMax.
I would stay away from AT&T. I've heard nothing good from them and they do, for a fact, have the worst CS of any carrier.