Unfortunately I keep getting older & new talent keeps coming out so I really can't answers the question correctly but I can agree that if I like the look of them I don't care how old they are.
Since the ones I all enjoyed were older than me - even though I hardly ever watch video anymore - I would say older, by about 5-10 or so years. The models in my mags however I would like younger, because they tend to be younger generally.
As long as it's Julia Butt, Deauxma. Sexy Vanessa, Vanessa del Rio, Luna Azul, Joanna Storm, Michelle St. James, Penny Porsche, Vanessa Videl and Lani Maru, older is fine by me
Don't have a specific age range as there are girls I like in all age groups. However if pushed to choose I would say the 18-24 age group as there are a greater variety of girls