I am in the same situation home in the country in MS and home in OK in major city.
I have the Verizon USB ULM 290 modem since we only connect with the one computer we do not need the MIFI. We have 2 flip phones.
So far we have never had a problem receiving 3G and most of the time we have 4G I do not download large files other than map updates from Garmin and the 5 GB is more than enough for surfing and most on line stuff but not movies.
For my use 3G is OK @ 5+Mbps However 4G is a lot faster @ 10+Mbps but for e-mail either one works just fine.
Depends on how remote your cabin is from a major highway or fair size town for reliable service. If you get good cell phone then MIFI will be OK.