I go with a decent brand (TrippLite, APC, etc.), look for at least 1000 joules, nice to have a protection guarantee with a substantial $ amount (check the fine print for weasel words), good to have phone line protection if you use a modem and/or coax protection if you use a cable modem, look for the UL label with a file no. - verify the file no. (lots of junk out there with bogus UL labels. Also look for the UL pass thru certification and verify.
.bh.