Verizon seems to have a very different corporate culture than AT&T. AT&T has at times made changes to their network that have negatively impacted existing users. Moving GSM off cellular bands and onto PCS for instance. Some people went to bed with four bars and woke up with none because of this change. They did the same when they were in the process of transitioning away from the TDMA network. I can't recall Verizon ever doing anything like this.
Verizon also seems to make more of an effort to invest in their infrastructure. 190 cities with LTE? FiOS deployments? What has AT&T done?
I'm not a Verizon shrill by any means -- I dislike their arrogance a great deal. It's just that the choice between them and AT&T is not a particularly hard one to make. Both will bend you over but the difference is Verizon won't skip town when you get pregnant...
Anyway, AT&T may be competitive amongst the masses but for those in the know it's a different story. Hell, even non-technical folks in certain markets have wised up to AT&T's nonsense. You don't have to be a techie to understand dropped calls and a congested network (ever known an AT&T user in New York City?)...