Let's see, what do I know? In the US, Verizon and AT&T have the best networks. Sprint is #3. T-Mobile is okay when you stay put where they have a tower. I recommend the Verizon network.
But next is the plan. Verizon will sell 5Gbyte for $50. Tough deal IMHO. My average is 12Gbyte. So I found Millenicom.com where I bought an USB modem
for the Verizon network (no SIM) and pay $60 for 20Gbyte. It registers as unlimited with the Verizon manager. No joke, best deal in the US.
I stick that USB modem
in a Cradlepoint MBR95 router which can also uplink to wifi
and even do fallback etc. It can even do that while providing wifi
for your access too, so it's all-in-one.
I use a Wilson external antenna
for the USB modem but only need it now and then.
I don't use the Cradlepoint for our wifi access, which is done with an Apple TimeCapsule, configured as bridge to the Cradlepoint. This gives me the 5GHz band and a big disk for wireless TimeMachine backups.
This works so well that I installed a second Cradlepoint router in our dinghy
(which is a car while land cruising). When we go exploring, I just stick the USB modem in there and we have Internet.
This is all 3G because 4G is still limited coverage and not in the backwoods where we tend to hang out