We were just out on a trip for six weeks in the western US. Anywhere from Arizona to NW Montana over to the Olympic peninsula through Oregon to Hood River and back across Idaho and Utah to Arizona.
We have the T-Mobile Magenta Plan with three phones and two tablets. The tablet is only $20/mo per line since we have cell phone lines with them. Otherwise I think it is like $60 or $70/mo. We use 175-225 GB per month. Teenagers!!!
We also installed the WeBoost Drive Reach with the trucker antenna outside and the big white rectangular antenna on the inside. Bought the whole setup from Signalbooster.com. You may want to compare the RV 65 to the Drive Reach. You can use the Drive Reach when driving. And, it seems to have a more advanced system to find weaker signals. The RV 65 is the older system but just with more power.
There was only one time in six weeks where we did not have a signal with the booster. Was able to stream on YouTube, Netflix and Amazon just fine. We boondock a lot off the beaten path. T-Mobile has gotten a lot better with coverage. Was considering Verizon or AT&T before the trip but T-Mobile seems to be good enough for us. The booster made all of the difference. Lookup RV with Tito on YouTube. He does a good job of comparing them.