I bought a Bell Biv Devoe album from a charity shop in Tunbridge Wells a few months ago.
It is ace.
New R&B, well: I like Fantasia, K Michelle, and Quadron. As for Corpsey's point above, too much of what's called R&B these days is EDM/trap-based; the aforementioned are all kinda trad r&b, but there isn't much in this style, or at least that you're likely to hear about without endlessly trawling DatPiff for tapes.
There's a new TLC track for their greatest hits which is basically their old sound but somehow not as good (the lack of Left-Eye probably has something to do with that, and the presence of Ne-Yo, too).
For comparison, some classic TLC (awesome freezeframe too):