I think both are equally enjoyable for me.
(I'm not sure if you mean "Videos on xtube.com" or "Low budget porn with no plot" when you say amateur.)
Sometimes it's not just the sex or act that has been captured in film, sometimes it's the scenario that adds to it, a scenario one would see in amateur porn.
For instance there are a decent number of Cuckolding videos with Shane Diesel and a few other famous type porn actors and actresses. The whole idea of these videos is that there is a white guy who is watching his wife cheat on him with Mr. Diesel or another huge dicked black dude-- under various circumstances of course, and I doubt if any of those circumstances have happened more moderate number of times.
But I don't like a lot of the women in professional porn; I like my girls or guys to look real, like someone I could actually meet in the street, not like some puffed up teased out super model with stationary tits. And some of the guys look like nothing more than crispy, muscle headed, college dropouts who got lucky because they aren't "Ugly" and were born with a big dick.
Good thing to lean back on, like wrestling for injured athletes.
Sometimes Amateur porn can be boring or badly paced or sometimes the girls or guys are just too unattractive for me to get off to.
I have seen some ugly dick thanks to amateur porn.
And don't say I'm shallow... it's porn.