I say upfront I am at a regional BPP college, and I am pretty happy with my experience.
it depends what you want, there are quite big differences between the two, but it doesn't really matter where you go, one isn't really better than the other:
COL - open book exams, BPP - only statute books allowed in exams
BPP has better facilities from the centers I have seen in London and Manchester including communal areas, which COL doesn't have
COL LPC lectures are all online, BPP give you the option of doing them in person or online
Cost depending on the school you are looking at
Careers service at both are very good
Start dates are different - BPP starts 2/3 weeks after COL
COL do all the skills in the first week, BPP do them throughout the course
Variety of modules is different
I would have to disagree that the BPP in the regions isn't as good - every regional school has limitations compared to the London ones re: being close to London firms and access to speakers etc. BPP put all that stuff up online. Thre are some serious advantages to the regional areas aside from the money - the opportunity to be involved in as much pro-bono as you want, access to lecturers and careers advisors is much easier etc.