About 10 years ago I absolutely scorched a guy on a board similar to this one about getting a regular provider. He had a thing for a provider in CA and was gaga for her, and I thought he was loco. Hell, play the field and enjoy the ride, right? Since then, I myself have slipped into having a regular more than once, and while I was not quite as nuts about a single provider as he was, I did sort of like it, while still exploring.
Now, finding a regular has a few technical requirements, such as location, availability, and cost (which rather limits the field even in the most hospitable environments). In the end I found that was looking for three things. Physical attractiveness (duh, I suppose, but the providers who became my regs weren't exactly supermodels), passionate kissing, and anal play (not greek necessarily, but that was certainly desirable).
Surprisingly, two of the providers were AMP stock, who are/were in general more known for high volume and few extras. But both of my regs loved to kiss, and while I never had greek with them, we certainly tried with many prying fingers with never a "no!" Both had incredible racks and pretty faces. One got deported because she pissed off her partners and the other retired when she found new work. The remaining reg was a Caucasian provider with a great face and bod, but an unimpressive rack, however, Oh, did she like anal, and I could not get enough of her.
I've had a number of encounters with providers with great racks, pretty faces, kissers, and even greek friendly ladies, but my combo seems to be overall attractiveness, kissing, and anal play.