Forty years ago I liked models age 18-30 in porn, and that's still what I like today.
I prefer casual clothing that hot women I see on the street wear - ripped jeans drive me mad - and that tends to be worn more by younger models, because of stepdaughter or student scenarios. Those scenarios don't do much for me - the whole incest thing is a big turn-off for me, to the point that I deliberately try to ignore the dialog in some videos - but the outfits are great.
Huge boobs and duck lips are a turn-off for me, and those seem to be more of a default among MILF videos.
One way my tastes have changed is tattoos; I used to be completely indifferent to tattoos, and now I find them an enormous turn-on.