Well, the received wisdom on here is Blair St, hands down. I've not been to London St since Lucy (now NTS) left, so I've got no direct experience. Word is that there's plenty of good looking EEs but shit service.
My go-to in BS is Vivienne. She's been there ages but still a brilliant service. She's Latvian/Russian mid 30s with a tight (nearly but not quite muscly) body and the best, well proportioned, fake tits I've ever seen. She's relaxed her "only OW" rule in the last year or two and her OWO is great. A brilliant fuck.
She works two or three days a week but when she's on, she's there 10.00am-10.00pm.
There are other BS "superstars" that have their fans on here, like Heidi, but they're a bit overrated IMHO.
Enjoy!