On Fri, 17 Feb 2017 16:11:10 -0800, sms wrote:

For users that never travel outside of urban areas T-Mobile is usable,
but if you like to travel to, or through, rural areas, it's not a good
choice.

I travel a decent amount around northern California, given I have grandkids
in various schools and kids scattered about with family.

T-Mobile is fine.

Since none of us are gonna run our own tests with three phones in our hands
for weeks on end, I would guess the coverage maps are what we'll have to
use.

What's the best coverage map site that covers all three carriers?
We can arbitrary pick where you live and where I live and see how the
coverage goes.

Here is OpenSignal for, say, the middle of Cupertino, for example.

All I did was:
1. Go to https://opensignal.com/network-coverage-maps/
2. Pick the carrier
3. Type in "Cupertino, CA"

I left the zoom level and everything else exactly as it was found.
AT&T http://i.cubeupload.com/2NuF7b.jpg
T-Mobile http://i.cubeupload.com/o8kiZ9.jpg
Verizon http://i.cubeupload.com/dcfRhq.jpg

Looking at those maps, they're about the same, although I could argue there
are fewer holes in T-Mobile than in either AT&T or Verizon, but I'll just
say they're about the same which is a tenable assertion.