Seriously, you can't go wrong with either and you'll probably eventually end up with both. The question is are you picky like some of us and will go crazy with mods? If so, the Aquaracer will need a replacement day and date wheel, while on the UPO you can replace the insert/dial/crystal/crown/tube. At the minimum some UPO's suffer from the crown stripping in the tube so you would want to replace the crown/tube. I've invested 1k in mods for my UPO and I have a Aquaracer on the way and will have the day/date wheels replaced and the crystal AR'd.