I live in Brooklyn so space is a factor. I picked most my parts because I wanted it to run OSX and play games in a microATX form factor. Pretty much its a hackintosh with a gtx970. It's not the prettiest inside. But its effective and runs surprisingly cool.
Case: The case was where I started. The Rosewill Legacy U3 is the smallest microATX I could find. If it had an intake fan and dust filters it would be perfect. One thing to note is that this case sucks for hard drives. Theres literally no space for them. They say you can do 2x 3.5" drives or 2x SSDs and 1x 3.5"drive. This is impossible if you have a big heatsink. Luckily I only had 2 SSDs.
Heatsink & Fans: I wanted silence so I went with Noctua fans. I heard the fan that comes with this case was terrible so i got another one for the case. It's true. Its dead silent.
CPU: i7 4790k because I can.
Memory: 32gb because I can.
GPU: GTX970 because I can.
PSU: EVGA SuperNOVA 650 GS Power Supply to match the EVGA GPU and the silent idle mode.
Monitor (not listed): Acer G257HU smidpx 25-Inch WQHD (2560 x 1440) Widescreen Monitor 1440p for $278.97