The grass is always greener as they say. You left Verizon for AT&T, and now you're going to leave AT&T for Verizon. When Verizon doesn't suit your needs in another few years, are you going to head back to AT&T?
As others have said, it all depends on the coverage provided where you frequent. You said both offered comparable coverage, so if you were happy with Verizon's voice quality and coverage, then stick with them. Of course, I believe AT&T is recognized as the largest BlackBerry carrier, so if you want the widest choice of devices, you might want to stick with AT&T.
So there... my offer to help is a response of non-committal to any particular carrier.
Semper Fi 3/2/2
"Wow" is now overused. Therefore, I will use "Magic bananas" instead.