I built this for mostly gaming and productivity. I went with the i3 6100 to start with and plan to upgrade to an i5 K chip as soon as I can save up the money. The machine is working great and I love the look. Sometimes the 2 cores seem to be a problem, but it's only been a couple weeks, so I'll have to wait and see.
Here's a video that walks through the build: https://youtu.be/fY98dN9oBQ0
I started out with a GTX 960, but got a little Xmas influx of cash and decided to go up to the R9 390. I liked the Nvidia software a little bit better but over all the R9 390 seems to be a much better performer. This is my first non-budget build and I'm coming over from gaming primarily on console so I'd be interested in what people think and where I might go from here.