There is no best, just what's best for you. How do you watch your movies? Netflix, Crackle and others are on the Binge on list for T-Mobile and don't count against you data. I've never used the 5 gigs of data I have on a T-Mobile hotspot and I stream daily.
I have Cricket and 4GHS has started selling a Cricket like unlimited hotspot service with the cost varying depending on the speed you need. It runs on the native AT&T network, no roaming.
Cricket itself has unlimited for $65 but there is no hotspot just like it's parent AT&T's unlimited plan.
As a business there are Sprint options for unlimited for under $50. Like with any carrier you have to make sure you have the coverage and Sprints is suppose to be the most limited. Have good coverage and it is fast and getting faster. Unfortunately that's usually somewhere near a large city.
Verizon is king of coverage and it proved itself when my Verizon hotspot stayed connected in the mountains while the other came and went. Unlimited Verizon high speed cost the bucks.
I have bits of data on each network because of where we camp. I'm just hoping for a signal for email, forums, and weather. Rather than depend getting a signal strong enough to stream, we use a tailgater portable satellite. It gets a great signal even at 10,000 ft, the picture is always HD and it never ever buffers.