I use a Verizon 4LTE USB modem (air card) and plug it into a Cradlepoint router.
My lady has AT&T and my Verizon coverage is usually better than her AT&T coverage (at least in the off-the-beaten path places where we usual travel).
Both Verizon and AT&T trumpet their 4G LTE coverage, but neither of them have very much 4G coverage (at least where we travel).
Many of the cell sites are so overcrowded that you won't get very fast download speeds whether it is 3G or 4G. Yes, in the middle of large cities you might get decent download speeds, but not usually out in the boondocks.
Seems to me that you have the right idea--using yorur own hotspot so that more than one computer can use the internet at the same time. But don't expect miracles from any of the providers.