I love army green/olive, but I don't tend to think of it as a neutral (although I can see how one might -- it's not a very "definite" type of green, is it?). Certain shades of army green are probably my "best" (i.e. most flattering) colour.
My favourite actual neutral is black, simply because I like it a lot. I do need to wear mascara and lipstick if I'm wearing black, though.
My second favourite is a medium heather grey, followed by charcoal.
I also like navy, dark brown and even beige, although I don't have a lot of any of these in my closet.