I've seen LTE connections slow to a crawl in a busy airport. T-Mobile and Verizon are pretty quick in LGA, but when you've got so many people using their phones for high content activities, it will bog down their networks too. The best I've been able to manage on T-Mobile in LGA is about 6 Mb down (oddly 12 up), and less than that on Verizon. The benefit for Boingo, is that once you're on one of their nodes, it is pretty stable. They seemed to have fixed the bandwidth issues they had at LGA from last year.

I'd rather use my hotspot connection than pay for the service, but at the moment, Boingo simply works better.