Seconding Cyberpower. Even their cheaper ones do better than BackUPS and don't fail to pass mains power along if the battery fails a check. The PFC Sinewave you

Seconding Cyberpower. Even their cheaper ones do better than BackUPS and don't fail to pass mains power along if the battery fails a check. The PFC Sinewave you linked do some nice power conditioning. It's a big help for me when my house switches to backup generator. (Why yes, I live in California, land of multi-day power outages. Why do you ask?)