My favourite shag of the last few years has been a (British) black girl and I do get a certain special
frisson from banging one. But that's really just me, I used to feel the same way about Asian chicks before I lived in China for three years and they became normalized to my lizard hindbrain. In fact over there all the white expat girls started looking exotic to me because they didn't have thick black hair down to their arse. Men's brains are programmed to seek out genetically different women I reckon.
There's nothing innate about being black that makes you a better or worse shag. You can't even read anything into where someone's from by their skin colour any more never mind what they are like in bed. Just yesterday I was looking at two early 20s girls who were both black, only to find out they were from Colombia. One had a negative review here so I didn't book in the end, but their pictures were hot. If I didn't know about UKP I would have gone based off their pictures and had a crap time.
That said, there's nothing wrong with liking some WG because you think they are exotic (though some idiots will say otherwise). One of the things I love about punting is that I get to see all the different varieties of women the human race has to offer. Right now there is a French Moroccan lady who has bid on an RB of mine who I'm really considering, as I have never had sex with an Arabic lady before (doesn't really count as Moroccans aren't really Arabs and she's mixed race in any case, but I am in London, not Rabat, so can't complain really).
I think your best bet would be to search UKP and perhaps AW for black girls with a good review/rating and 'likes' that you're looking for. You're more likely to get a session to remember that way. A quick UKP search for 'black girls' has this London based girl with a good recent review who still seems active for example:
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