The answer is....BOTH!
I initially planned this build just for data backup and redundancy but I had trouble stopping there, just as we all do. I store all of my important documents on one of the WD RED drives and Acronis then backs that up to the second WD RED drive. It is also configured to create a weekly image of this machine and a weekly image of my main rig. I initially thought of a RAID1 configuration but since this is not a true backup solution, I immediately adopted the aforementioned setup.
I also wanted to do some surround gaming on this machine so I simply purchased an R9 390 and voila, I had an extremely overkill home server and a highly capable gaming rig. I currently host my own teamspeak server, rust server with oxide and my minecraft server. I also plan on hosting my website in the near future.
i7-4790K: Intel Retail Edge Winter Deal
H100i GTX: Best Buy discount
SSD: Microcenter sale
GPU: Best Buy discount
CASE: OfferUp deal (open box)
Fans: Best Buy discount
PSU: Fry's deal. This one was initially $85 but Fry's had a sale for $55. It then came with a $25 MIR on top of that but my personal promo code wasn't working so they sent me to customer service for manual price entry. The person who rang me up didn't read that the $30 listed price was INCLUDING the MIR and charged me for only $30. This means that I basically got an instant MIR on top of the already lowered sale price. I then completed the actual MIR and got this PSU for nearly $5. Shady? I call it a win!