Trying to decide whether to go with Big or Huge. I figured it was just a seven point scale but it's hard to judge without a reference for what you mean by "MOAR". Are we talking biggest natural boobs that you only see on fatties like Norma Stitz, biggest natural boobs on a slim frame like Merilyn Sakova, or are we talking big fakies like Chelsea Charms?
In general I like bigger boobs, but shape > size. If you're sporting pancakes or gym socks, size won't save you. The reason why I prefer them is purely aesthetic, but like a few others have said they have to match the girl's frame. If you have big hips/butt then you'll look better with a big chest to match, and vice versa. Pear-shaped isn't particularly sexy, but neither is Danielle Derek (though for some bizarre reason, Penelope Black Diamond is... go figure).
I tend to like curvy girls with bigger frames, and since big boobs suit that frame I like big boobs too. Anything between Aria Giovanni and Karina Hart is ideal (considering the breast-to-frame ratio, not just bra size). Size starts becoming unattractive around the Ewa Sonnet level, but since hers have a nice shape she still gets a pass.
Have fun Googling all those names! XD