Here are two devices that I've tested a great deal and can recommend highly.
This TP-Link router picks up someone else's wifi hotspot from 100 yards away or more. It's a WISP router, meaning I can pick up a Comcast Xfinity hotspot from a neighbor's house, and then turn it into my own wifi hotspot with a different name.
Comcast has blanketed the US with wifi hotspots. Most folks with Comcast internet become unknowing and unwitting broadcasters of Xfinity hotspots. When I am on the road or at my summer house, I use this TP-Link router to get an Xfinity signal from a neighbor across the water or from a far-away RV park hotspot, and it is plenty fast. Not enough for streaming video, but good enough for everything else I need to do.
Folks are using these TP-Links with their RVs, also setting up two of them to talk to each other, supply a remote cabin up to a mile away from the main house with internet.
This is not very portable, so I only set it up if I am going to use it for a few days in the same location. It is an incredible tool for picking up wifi signals from far away that you can then use. (I am a Comcast subscriber at our main home, so have a username and account that I can use with their Xfinity hotspots).
I've been using the Freedompop free cell phone and cellular hotspot services for three years. Freedompop really gives free cell phone and hotspot service -- but you have to be aware of the "gotcha's" and disable things like their premium services, which adds charges.
Freedompop's customer service through Twitter messaging has been GREAT. I've received better customer service in the past month through them than I've ever had from just about any company. That's either saying a lot -- or maybe it's sad that I am getting such poor customer service from all the other companies that I deal with.
I have noticed that a Samsung Galaxy S3 phone, with Sprint's 3G and 4G network, has not been working as well as it did. I believe that Sprint's 3G network might be getting less attention from Sprint and degrading in area and quality. Sprint's 4G network seems to be getting better, but the area it serves is fairly small compared to Verizon's.
I recently bought a FreedomPop Netgear Zing hotspot. This device takes a cell phone signal (4G) and lets you access the internet through Freedompop's (Sprint's) cell network. I have been very happy with how fast this hotspot works, at my summer house, which seems to be on the edge of Sprint's 4G network. This wifi hotspot uses cell data and is plenty fast. I get 500Mb of data to use monthly with this hotspot for free; I have not opted to pay for the 3G fallback data.
The Netgear Zing hotspots always show low battery and no power warnings; but despite the warnings, they have been working fine. I will have to see how long they last. I've only had one for one month; but I've been so happy with it, that I bought another. Freedompop has been selling them for $20. The Netgear Zing hotspots DO have 3G fallback capability, from what I could tell -- but that costs $3.99 per month. Using the hotspots only in 4G mode is free, if you only use up to 500Mb of data per month.
Using Freedompop is free but you need to know how to turn off the gotcha's.