I know of Royal park Flats (I live in the same area), it's on a busy road so may get noisy, but the entirety of Leeds is noisy
I didn't even know Leeds uni owned the flats, but they've been refurbished over the summer so should be nice
In terms of safety, you have a main front door, then the door for the flat, as long as you keep the second door locked you will be fine, its the houses that usually see crime because people don't lock the door behind them
It's only post-grads in there, so the noise from other flats shouldn't be bad, decent 15 minute walk (uphill!!) to uni, plus there's a sainsburys across the road (24 hour one close by too)