I've got offers for MathStat from Warwick, Bath, Leeds, Lancaster and Surrey. For me, it's between Bath and Warwick.
for you, I guess you shouldn't bother considering Southampton or Manchester because there is such a gap between your top three and them.
Imperial is is very well respected, but it's London based and extremely rigorous
Warwick is also great for employment and extremely strong in maths, but it's location and social life isn't ideal for all
Bath isn't quite as respected as the other two, but it's a beautiful place and it's links to industry are phenominal