Do not get a 840 Pro, no actual reason, Crucial MX100 256GB can probably save you 30$.
Obviously can save money from getting a different case, but i suppose you like looking at that.
No reason for 16GB RAM if its WoW only (No actual reason generally but its safer to get 16GB for heavier games, for WoW, no reason), save yourself 100$, no reason for the "Pro" ones or 1866Mhz too, 1600 will do you just fine but generally no reason for 16, save yourself 80-100$ from there.
The asus board is 150bucks really, and its Z87 not Z97. You can flash the mobo to support the 4690k but honestly why get into that when you buy a new pc, just go for Z97.
- Went for a red/black theme, thus why i chose the gigabyte gaming 5 which is on same price as Asus Z97-A. Both are the same in any way.
- 8g of ram is alot to game, 16gb is not needed.
- Cpu cooler is of similar quality, looks alot better and its cheaper.
- Similar ssd for cheaper.
- Added a WD 1tb storage drive, optional.
- Better case while cheaper.
- Msi gpu is clocked higher for same price.
- Same quality power supply, modular, its seasonic oem, 660w is too much anyway, the system at full load is like 350W.
- Left the monitor alone as its a good deal for its price.
- Don't see a reason to get an older o/s, the newer one will be supported for longer.
- Intel wifi adapters are the best.
- keyboard and mouse is what i would prefer. Same keyboard with mx-brown switches and an mmo-mouse.
All in all its same or better for cheaper. You can even get an i7 4790k in there and still be cheaper if you don't want to mess with overclocking too much or you haven't got the time.
Mouse/keyboard is obviously personal preference. Most of the motherboards around $100-150 range are decent/good, can pick which ever brand you prefer or has some specific feature/aesthetics you're looking for.
We're at the point where if you want 16GB, get 16GB. My usage sees between 8GB and 12GB of RAM used, and that's multitasking on two monitors, lots of Chrome tabs (Google Drive documents), WoW... if I want to run updates in the background, I have RAM to burn on it. It also allows me to turn off my SSD's pagefile which improves random write usage drastically. After using my PC, two of my friends upgraded from 8GB to 16GB and one more tried but his crappy Gateway won't accept more than eight.
Of course if you don't need it, don't get it. However, even office work can see a benefit from 16GB RAM.