Hitomi Tanaka is one of my all time favorites. Her teacher porn is some of the best, in regards to Japanese/Asian porn. However, it is censored; are you looking for US Asian MILF. Ava Devine has had some great MILF porn as.
I'm fond of Jinguuji Nao in general, she's just a good actress overall (not just the sex scenes, the actual plot stuff too). Not so much mom/milf porn, but the slightly mature roles: think late 20s/early 30s, OL/wife/daughter-in-law roles.