I use lots of UPSs, because the power at my office often goes out for a few seconds at a time.
My experience is the APC ones are the most reliable. I’m sure there are other good brands, but APC tends to have aggressive discounts on their government pricing, so I buy lots of them.
I’ve also bought Cyberpower and Amazon because of their lower price, even after the government discount. As long as the Cyberpower ones are working, they are fine, but they are very unreliable at notifying me when the battery is dead. Similar story with Amazon. It worked fine, until one day when the power went out, and I found out the battery was dead.
The APC ones are just like a smoke detector—they will start beeping at inconvenient times to let you know their battery is dead. If you’re protecting anything important, this is worth the trouble.
If you’re protecting stuff where the battery backup is merely a convenience, then getting a cheaper one might be worth the trade off of an unexpected failure in 4-5 years.
In my experience, an APC UPS in the $50-70 range will run a cable modem and WiFi for a long time; possibly hours. If you want to protect a desktop computer, then I recommend getting its own backup.
When I had my internet gear and house server, a repurposed desktop, on a single UPS, it was fine for the 2-3 second outages, but for anything that ran into minutes the computer would run the battery down to 20%, and then the computer would shutdown, leaving the cable modem running of a nearly drained battery.
Sure, I could have spent $250 on a big UPS that could run everything, but I’d rather have the server shutdown if the power is out for 5+ minutes, but have the internet stuff run for as long as possible. Two $50-70 UPSs was the answer.