I've been happy with CyberPower's 1500AVRLCD. Currently own two of them. Last year when I was looking for an UPS I declined APC due to their proprietary USB cable and it wasn't clear to me their models were HID compliant.
I have a Belkin 1500 VA UPS. I have the Mac Pro and 30" Cinema connected to it. We get a lot of power outages in our area. It gives me plenty of time to save my work and shutdown.