While AT&T phone service and 3G data speeds are very good where I live, in Buffalo NY, their LTE rollout is pathetic. Verizon had LTE here in Buffalo back in October, but AT&T has their list out through this summer and still nothing.
Since the major factor in me staying with AT&T is that GSM can do data and voice simultaneously, that doesn't apply to iPads since they aren't phones. I seriously thought about a Verizon iPad. But the resale value (got to think about iPad 4) of GSM iPads is up to $100 higher. But it is a serious possibility I will have the iPad 3 for its entire life span, until next years upgrade, without ever seeing the LTE speeds.
I live in Buffalo as well. I also considered resale value when choosing an iPad, but keep in mind that unlike the Verizon iPad 2, the Verizon version of the new iPad has an unlocked SIM slot just like the GSM iPad 2 and the AT&T version of the new iPad. Having this SIM slot is what gives the GSM iPad 2 higher resale value over the Verizon iPad 2, which is useless internationally.
Because of the reasons you stated, I went with a Verizon iPad this time. Verizon has LTE in Buffalo and a lot of other cities where AT&T has yet to even announce LTE plans. The fact that Verizon allows you to use the iPad as a personal hotspot is a plus too.