I can get a foot long one if I beg enough, but it takes a while and I haven't had a foto long one in ages. XD
But over that, the Meatball Subway is definately my favourite.
But I also like the BMT, Turkey Breast and ham, ham and my own custom one with Bacon, Chicken, Pizza sauce, double cheese and some other stuff.
The pizza sauce is brilliant. xD
EDIT:
Oh! And the chicken Teryaki! xD