You don't decide by price. Free cellphone service is useful if you don't get coverage where you need coverage.
First determine coverage. (For instance, where I live, there's a whole town that AT&T doesn't cover at all, but TMobile covers like a blanket.) Verizon covers more places, AT&T covers more people, meaning that their coverage covers different places, places with more people who will use AT&T. (Which is why the situation here - most of the people in that town are on Lifeine covderage, because $5/month is far too expensive for them.)
Then, IF AT&T covers every spot you need (and since dead spots can be as small as one square foot and a few inches thick, I mean "spot", not the street in front of your office building, but sitting at your desk where you usually sit, and on your desk where you usually put your phone), it's your choice.
"About the same" could easily mean that Verizon gives you the coverage you need, but AT&T doesn't cover a single place you need. Need to call your wife, and can't use the office phone so you'll just use your cellphone? But there's a blizzard in progress and it's 4°F outside - and you checked for AT&T coverage in the parking lot - but not at your desk? Happy snowman by the time she answers the call.