Unless you're very posh go for UH.
I'm on Freshers crew this year and it's going to be sick. We've hand picked the people who will give you the best time. Rooms are no smaller than the Hiatt Baker rooms, but smaller than Wills. En-suites are slightly excluded though I'm mates with a few of them from one of the blocks and it's no real issue.
Gym is a bit of a mare from Stoke-Bishop, if you're looking to focus on the gym/MMA stay in one of the Clifton halls or something as it will usually take an hour or so travelling (there and back) to go to the uni gym. If you bring a bike it's not a big deal though.
As for Goldney vs UH - if you want a good time, go to UH. If you want a nice building, go to Goldney. The one time I went to Goldney this year for a night out it was an absolute joke, very, very boring.