If you want an uber gaming PC now ($1700):
https://pcpartpicker.com/list/L9JLgwIf you upgrade the CPU when Zen 2 comes out ~Q3 2019 ($1400, then sell CPU and upgrade):
https://pcpartpicker.com/list/nFthw6DON'T get a 2700X unless you're actually doing video editing/streaming (let us know if you are, as you need more RAM and there are better CPUs for it). If you want cheaper now to upgrade, there's no reason for getting a 2700X, it's just a more expensive part to try to sell later. 2600 -> Zen 2 is the way to go.
Tomahawk for the motherboard, as MSI's motherboards are the best for overclocking atm in terms of VRM and capabilities. Price is not everything.
When looking at cases, having 3 fans in the front isn't always the best if they choke them by putting them 1mm from the glass front panel with no inlets. Personally some of my favourites are Fractal Design, like the Define R6, Meshify C and Define C. But again, personal taste.