I go KCL for law and teaching here has been excellent. it also has the London buff w/ networking and whatnot. arguably they're both on-par for law, and not much behind UCL and LSE really and especially not in terms of graduate opportunities. you'll see a very big number of Durham and KCL graduates at top law firms.
imo, the thing that should make up your mind here is whether you'd prefer to be in a big city or a quiet city (town?).