My next purchase, asuming nothing breaks that needs replacement ASAP, would be wheels and disks. Im thinking
XT disk hubs
Mavic F219 rims
Avid mech disks

If I ever find the money to put in the order for those ill be doing well, but if I do find more money I can replace my bars, stem, seatpost, and seat, and I will have all the extra components I need to rebuild my old steel hardtail, for riding things that are likley to break my bike.