What I'm interested in is if anyone has recent experience with both AT&T and Verizon, and how you would rate the AT&T service in remote areas and inside buildings, as I'm often buried inside of them doing IT work in basements and wiring closets.

The reason I am here is because I'm thinking about going with AT&T because:
- I will be working back and forth between here and the country of Colombia where they only have GSM.
- AT&Ts Note 4 N910A is compatible with all of the bands currently used in Colombia, and Colombia is also adding bands that fall right in the N910A's lap. That is not true of the N9100 Dual SIM, and the Dual SIM only does GSM and texting on the second SIM. Moreover, it doesn't support AT&T's B12 & B17/700 bands, which I would assume penetrate buildings better.
- Colombia's pay-go works more like our TrackPhones where you buy minutes, plus they are like we used to have with calls to the same carrier being cheaper. The N910A also has a removable back (and replaceable battery and 128GB MicroSD), and with the SIM slot behind the cover, it supports a multi-SIM adapter, so you can use multiple networks, just not simultaneously as with a Dual SIM.
- My current phones will work there, they are not compatible with their LTE, LTE is cheaper to use, and there is available.

Thanks!
PS:
Currently we have a Note 3 on Verizon pre-pay because I couldn't get the phone I wanted at the time from Sprint/Boost, and a Note 4 on Sprint/Boost. (Actually, Sprint/Boost beats Verizon a lot of places in the Midwest, which was prior a very heavy Nextel area.)