I have a 4s on AT&T, and originally ordered the AT&T iPad, but then went to the Apple Store on Friday and bought the Verizon version. Took the AT&T version back that night. The hotspot was the real kicker for me.
I got the AT&T because I love the free AT&T basic wifi that you get with any level of cellular data purchase. I stay at Hilton enough that it makes a diff to me. Also the $30 for 3 GB fits my travel needs. When I don't need that, I can drop back to the $15 plan and still have the AT&T wifi and enough 3-4G/LTE for those times I don't have wifi. Also even the 3G data on AT&T is really fast and solid in most cases.