Think I can talk on this one with reasonable experience: I'm a french/politics student at Aber, I'm from Kent and my mother is a lecturer at Kent - and she went to Aber! For french, definitely, you'll be better off at Aber. It's a small department but pretty darned good, and I've never had any complaints. Kent however have scaled back a bit so it could be a disadvantage. place-wise Canterbury is nice but definitely more expensive. It's one and a half to 2 hours from there to London, compared to Aber's five hours on the train. Aber is cheaper, quite isolated but I absolutely love it. Canterbury has less students in proportion to normals, whereas Aber has more. Kent also only has first years to live on campus/uni-run housing whereas it's possible to do all three years in uni housing at Aber. Aber is much more compacted and everything is one place, and it's flipping gorgeous. and there's less rain, despite being in Wales. I know it sounds untrue, but compared to home? Less rain.
hope I've given you a few pros and cons. Obviously I'm biased towards Aber but have some knowledge of Kent uni.
@Codex, psh, last summer we had Pimms on Aber beach.