just to update..I have bought a sony a6000 mirrorless with kit lens. at first it felt awkward with the style but i am already get used to it. IQ is very good. i bought a lens adapter and i can still use all my Nikon lenses, with manual focus of course. but its not a problem with the focus peaking features. its fun to use. now im planing to get a few cheap prime lens nikon mount.
it is indeed a fun and yet a serious camera at the same time.
still looking buyers too buy D90 . but i have no regret switching.