I would like to put my name in the hat for the Geforce GTX 960, the 256GB Samsung SM951 M.2 SSD and 6TB drive. Here's what I would do with each:
960: I am building a steam box for my son and a 960 would be perfect since he's only playing Lego games and the 960 can run these pretty smooth at 1080p.
M.2 SSD: I have a Maximus VI Extreme that had one of the first M.2 slots on it. I have never put an M.2 drive in it and would really like to see how it would work out as a boot drive (it does support booting to M.2).
6TB drive: I really need a big drive to do backups. Right now, I am only backing up to a 1TB. Because of the limited size, I am just backing up a mirror of my OS drive and all of my pictures and documents. With 6TB I could backup my steam directory!