Which carrier in reality has the better service and coverage? Att or Verizon?
That is the $64,000 question. I've struggled with this issue for quite a while and decided on AT&T. Of course, this depends on LOCATION, location, location! In my case, I get AT&T throughout most of Texas, whereas Verizon fails. Plus AT&T gives me over 1 mbps on 3G, which I think is pretty good for being many miles from the nearest tower.
However, if things are equal on your end, in terms of coverage, I'd pick Verizon due to their unlimited data plan.