You'll find when you zoom in the coverage looks more like a patchwork quilt than solid coverage
The maps that you posted Pnutt have no meaning since your Att map doesn't show which areas are 3g and which areas are 2g Edge. Att's Edge data speeds are so slow that if you are ever out of a 3g coverage area then you might as well not have any data coverage at all which is why I posted the following map:

So with Att in 5x more places your data speeds will hover around a snails pace of 0.05 - 0.1 mbps compared to the Verizons 3g data network that will get you around 0.5 - 1.5 mbps.
I currently have Att and like them alot since I live in a big city but I can think of 5 really big benefits of going with Verizon over Att:
1) 5x more 3g coverage (if you ever go on Att's edge network you might as well have no data coverage at all)
2) Tethering plan that lets you keep your unlimited (Att doesn't let you keep you unlimited)
3) Less dropped calls
4) Only carrier with LTE and will continue to have a far bigger LTE network in the future than other carriers
5) Has already officially said that people with 3g unlimited plans can upgrade to unlimited 4g plans and be grandfathered (Att hasn't said this yet)