^ This build has an entry level CPU that you'll probably want to replace at some point, but the motherboard will accept up to a Core i7 7700 if you find the Pentium is getting a bit weak. It has 2 extra RAM slots, and a reliable power supply that is more than adequate for anything you could put in it. If you wanted a slightly stronger machine from the start, you might choose to go with an i7 7500 instead (+$140) and a Radeon RX470 (+$40) or even a GTX 1060 (+$100ish).
If you wanted to go with a small form factor system, you could instead use this motherboard, case and power supply for a PC that's just as fast and has onboard WiFi, but takes up 1/3 the space: