Cricket is owned by AT&T. Other than a few places that AT&T would roam on another carrier your coverage will be exactly the same as AT&T.

I've had T-Mobile for years and must say as of late their coverage has gotten considerably stronger. Obviously each carrier has their stronger and weaker markets but I find them fantastic almost everywhere I am. Additionally coverage in Canada and Mexico is included at no cost and most plans feature unlimited music streaming and unlimited video streaming. Neither of those count against your data bundle. Additionally you get 5-7GB of hotspot data and and aircraft with Gogo inflight internet you can text for free in the air. I use the hotspot instead of the hotel internet because it's usually a lot faster, I'm using it right now. Also you can use any wifi calling anywhere in the world and it's like being on their native network. I travel a lot internationally and they include throttled 2G free data, 20 cents/per minute, and free text roaming in 120+ countries. They'll even send you a free LTE micro cell spot for your home if you don't have great signal there. Basically a mini tower in your own home.

I've flown with plenty of people who were surprised when I whip out my phone internationally and use it just like I was at home, meanwhile they're keeping their phones off so they don't get screwed by roaming charges.

There is a reason they are adding more than 8 million people a year, it's not the T-Mobile of old.

YMMV