What output power ranges of UPS's should I aim getting for this high-end system?

You might have answered your own question. When I don't know what to decide on parts I look for the best one I can afford without wasting money on too much overkill. I believe they are all good for power surges, Lightning struck near our house and blew out our tv but the $35 surge power strip saved our pc. All the major brands will be similar to the other major brands. They like to keep up with their competition.