I'm already discussing builds in another thread, but my budget is £1800 for the PC, monitor and accessories. It's a development machine for videogame and music production. I'll be casual gaming regularly and using software like Unreal Engine 4, Blender or similar, and FL Studio or similar with a Roland a-800 pro MIDI controller which needs to be lagless with no latency.
I've went from knowing nothing about PCs to learning quite a bit in the past few days. So I know that if I was solely gaming and just wanted all the CPU power to go into those kinds of tasks then the Z170 would be the choice, but if I was rendering and doing a lot of multitasking that X99 would be the way to go. Me personally I'm falling in the middle, this is to be an all purpose machine that's going to give me the most gaming performance from a GTX 1080, but I'll be using it for development purposes so for example I might be building and environment and testing an environment at the same time. With Blender I'll be using cuda cores most likely so I don't know how CPU performance will come into that. In the future I'll be getting a capture card, and I'll likely be using software like fraps for video capture.
But yeah, security is a big priority, I don't want wifi nor Bluetooth from the motherboard, just a wired internet connection that can be used temporarily for updates or perhaps for a little online gaming or streaming should I feel like it at the time.