RN
Two things share this name and they have almost nothing in common.
The first is a marketing category: a specific, highly capitalised production formula that a handful of studios have refined for years, with house lighting, house casting, recurring series and performers under contract. It is one of the most heavily produced niches in the industry and it looks like it — the budgets are visible on screen.
The second is a factual description of a scene's cast. It applies to an enormous quantity of material that was never made with this category in mind and is not marketed under it at all.
Both get the same tag. That is the whole difficulty.
What the studio formula actually is
Worth naming plainly, because being coy about it helps nobody: the commercial version of this category is built on racial typecasting, and the studios say so in their series titles and their marketing copy. Performers are cast to a type, the scenes are structured around a contrast the production wants you to notice, and the framing is deliberate rather than incidental.
You can hold two thoughts about that at once. It is an aesthetic formula with real craft behind it — these are among the better-shot scenes being made in mainstream production, by some distance. It is also a formula that puts a small number of performers into a narrow, repetitive lane and pays them to stay in it, which is a working condition worth being aware of even if it changes nothing about what you watch.
What it means for searching: this material is findable by studio and by series, and hardly findable any other way. The formula is the product, so the brand is the index.
What the descriptive tag returns
The other half is everything else — amateur uploads, scenes from studios working in unrelated niches, couples filming themselves — tagged by whoever put it up because the tag describes what is visible.
This half has none of the formula's characteristics. It is not lit that way, not structured that way, and not trying to be. For a lot of people that is exactly the appeal, and it is the half that the "best sites" lists never cover, because it has no brands attached and therefore nothing to rank.
If the produced version's framing is not what you are looking for, the descriptive half is where you should be searching, and the way in is not this category at all — it is amateur and black porn sections, where the material is filed by who made it rather than by what it is being sold as.
Reading a site in this category
Three questions separate the useful sites from the rest, and none of them is about catalogue size.
Is it a producer or an index? A studio site holds material it made and can tell you when. An aggregated tube holds clips of material other people made, often trimmed, often re-encoded, sometimes years old and presented as current. Both are legitimate; they answer different questions.
Is the roster current? The most reliable freshness test on a paysite is the release calendar, not the front page. A site running a weekly release has a production operation behind it. A site with no dated releases is selling access to a back catalogue, which is fine if the price reflects it.
Is the pricing visible before the join page? Anything that shows a price only after an email address is a decision, and it is not a decision made in your favour.
Where to start
The directory maintains a free section and a premium section for this category, and the split between them tracks the two halves above fairly closely — the studio formula lives on the premium side, and the descriptive half is spread across the free one. Which of the two you want is a question you can answer before you click anything, and answering it first saves more time than any ranking would.