Eh. I dunno.
My porn preferences change from day to day and hour to hour, but always lean heavily towards still photography.
There are also times when I'll click on a single thumbnail, get over to the set of photos and go "Well, I can see why they picked that one as the link, she looks like she's pilled/stoned out of her gourd in all of the others. Probably was just to get through it, poor woman." which is a massive turn-off for me.
I much prefer the "I'm doing this because I LOVE IT" look, but that'll typically transcend skin color, breast size, a fair degree of weight, and quite a bit of age for me, and just be dependent on what strikes my eye at the time.
Over the past few years I've been drooling more at blondes more for some reason. Prior to that it was mostly brunettes, and waaay back in my junior high/high school years it was mostly redheads, for example, but of course back that far it was basically the Sears Catalog.
Maybe it's like music.
Some people really have a particular preference and others don't.