It is as you suspected - pornography is popular. Maybe the adult cinemas and stick books have taken a pounding and the age of those climbing the forbidden stairs to shops with an X rating is increasing. But online
Pornhub, a Canadian site, is at position 38 on Alexa and 24 on SimilarWeb. Other porn sites featured are [Alexa rankings]
LiveJasmin (47),
TXXX (77),
xHamster (81),
Bonga Cams (83),
XVideos (117),
Redtube (217 -
97 on SimilarWeb) and
XNXX (258 -
31 on SimilarWeb). To round it out, let's include another couple featured on lists for the number of hits or amount of traffic:
T'n'A flix and
Youjizz. Only that cuts out
Tube8, Beeg and
Youporn. More porn than you can shake a stick at
II
This necessarily comes with a disclaimer. If you are encyclopediac in your endeavours, at some point you're going to come across erotica and, whatever your own attitudes, decide to either include it in order to be truthful and comprehensive or omit it on the off chance that this little chunk of cyberspace will hold any attraction to minors.
For that reason there's only one hyperlink that leads to the site itself and it begins with X-V
Those searching for the appropriate level of titillation are unlikely to search by the name of the website. The search terms they do enter then take the panting viewer to sites of varying degrees of quality and consideration.
The arty photographs in Beeg looks pretty good but it's still hardcore porn so I decided not to hyperlink to it.
As with websites, there are a number of website directories that are now defunct including 
