What I like the most is actually reading porn, not watching it. But your question was about watching so I'll focus on that.
I do watch porn, although not very often. I need to be in the right mood for it. In my opinion, porn is good if you don't abuse it, like most of life's pleasures. For instance studies show that porn availability correlates with decrease in rapes.
Not that I think most people would rape others to begin with, but it fits with my use for it, which is for release when I'm under sexual pressure.
It differs from my enjoyment of written porn, which I do for completely different reasons. I feel like all books should have the sex scenes in them, so to me erotic books are just the way normal books should be. Same with movies, really, I have always found it weird when the whole point of a story or plot point is the relationship between two people, and when they finally get together it's cut the second they start kissing, then we see them after the fact.
If it's relevant to the story, why do you cut it out? It feels to me like replacing every marriage scene with them arriving in the car, then leaving in the car the next second, skipping the character development that could happen in the meantime.
But for movies, I understand that actual people are involved, so I find it less of a problem. For books, though, cutting it out feels to me like I'm reading the censored version of a better book. It annoys me.
Sadly, erotic books can have the opposite problem of being focused too much on sex, but fortunately, not all of them do, often it's a very minor part of the story.
For all media, I have an issue with finding things that do it for me. Books written for women tend to have an emphasis on cunnilingus or fingering, neither of which I like, and lack fellatio, which is my favourite. Videos tend to feature men who don't look enough like men I know to allow me to fantasize about them (I'm usually too busy thinking about how much these huge penises would hurt me) and lack focus on the men's faces as they orgasm, and the males aren't noisy enough.
For visual porn, I also prefer material that doesn't feature females. I started by watching handjob videos, and in one of them there was a second man who started giving a blowjob, and I suddenly realised that gay material would be perfect... I thought. It still tends to emphasize big penises and show the penis at the time of climax rather than the face.
Also for all media, they tend to lack realism. The erotic books tend to have idealized pink unicorn versions of sex where the woman always comes several time, the last at the same time as the guy, and the videos or comics tend to have very specific body types that aren't that common, and cut off some important parts. And neither have nearly enough fumbling around and laughing about it.