If you wanted to blow the whole lot on headphones, I would go for k701/k702, or hd650, but I would bo try them if I was dropping that sort of money on headphones. If you wanted to get headphones, and midi I would go for some k240(love mine), or hd280.
As for midi keyboards/controllers their is to much to think about, like how many keys, after touch, pads, ect, just don't buy anything M-audio imo.
If I had £300 for gear (which I don't