One time I was laying on the beach and the signal wasn't as good as AT&T, but other than that it's same or only slightly weaker but still great.
Oh, the signal is almost nonexistent at Waterford Lakes Town Center (-114ish), but I think AT&T was also. I actually switched from AT&T because the signal in my house was crap with AT&T and visitors with Verizon (-108ish), but those with MetroPCS and T-Mobile were near perfect (-70).
Plus T-Mobile uses WiFi calling when available which makes it even clearer.
If you switch, download T-Mobile Tuesdays app. Every Tuesday you click a button and get free stuff in the app. Usually free movie tickets on Fandango, pizza, free lyft ride every Tuesday, and more.