Jack the best advice I can give is go and find out for yourself. Everyone on here will have ther own fave resort so you willnot get a true picture. Mine is Pamps simply because I have been 3 times and am off this weekend. Borovets does seem to attract the most complaints though!
it depends wether your begginer intermidiate or expert os just looking for the night life.
begginers - pamps
intermidiates - borovets/bansko
advanced- bansko (hardest runs i've ever seen!)
night life - bansko because it isn't purpose built and has loads of little taverns in the village (village pop 23,000)