I found that any of these hotspots can provide a quick and convenient Internet connection. Which one you choose depends on how much you're willing to spend, how important getting top speed is, and how much time you have left on your current data service contract.
How I tested
To see how AT&T's, Verizon's, Sprint's, and T-Mobile's mobile hotspots compare, I used each of them every day over a three-week period. On top of using them for daily Web excursions, I watched online videos, listened to Internet radio, posted material to a website, made VoIP calls, and downloaded and uploaded large files.
I conducted my online speed tests over the course of five days: three days in my office, and two days on the road in New York, New Jersey, and Connecticut. While mobile, I tested in a variety of environments: while working out of my car, on a moving train, in a hotel lobby, while waiting at the airport, and even at a nature preserve.
At 9 a.m., 1 p.m., 4 p.m., and 9 p.m. each day, I simultaneously connected three clients (a Lenovo IdeaPad U260 laptop, an Apple iPad, and an Archos 70 Internet Tablet) to each of the hotspots in sequence. To simulate the needs of a small workgroup, the iPad played online videos 10 feet from the hotspot, while the Archos tablet played an Internet radio station from eight feet away. The laptop was set up four feet from the hotspot and measured the available bandwidth with Ookla's Speedtest.net bandwidth meter. I recorded three latency (ping), download speed, and upload speed results for each hotspot at each testing time, and when all the data was compiled, I averaged the results.
To see how long each hotspot's battery lasted, I started by fully charging each one overnight. With the hotspot about five feet from a connected PC continuously playing YouTube videos, I unplugged the hotspot and timed how long it took for the battery to die. While it was running down, I monitored the hotspot's battery level using its setup screen's battery gauge.
Finally, I measured each hotspot's Wi-Fi range. With the hotspot at one end of my office and the IdeaPad U260 notebook connected, I ran an Internet radio station and slowly walked down a long hallway. When the audio content began to lose its wireless connection and started stuttering, I stopped and walked back and forth a step or two to confirm the location where the network's signal died, then measured the distance back to the hotspot.
AT&T: Novatel MiFi 2372
If a bargain price tag is more important to you than speed, grab AT&T's Novatel Wireless MiFi 2372 hotspot (available for $50 if you buy it online and sign up for a two-year data service contract, which costs $50 per month). It's an inexpensive way to get online, but its performance lagged behind the others.
Weighing 2.7 ounces and measuring 0.6 by 3.9 by 2.4 inches, the MiFi 2372 will easily disappear into a pocket. The lightest but largest of the three mobile hotspots, its black-with-chrome styling is a little ostentatious compared to the understated Samsung SCH-LC11 offered by Verizon.
The MiFi 2372 includes a handy MicroSDHC card slot for saving and sharing up to 32GB of data. It has the simplest design of the three devices reviewed here, with just one LED light that shows that it's transmitting a Wi-Fi signal; it lacks extras like the the digital ink screen on the Sprint hotspot device that shows what the signal strength and battery level are. The device ships with both an AC adapter and a USB cable for charging it from a computer.