Of these, the 8700k. Best by performance per dollar, Ryzen 2600. Best keeper without going nuts with the price, Ryzen 2700. Please don't pick an i5.
The graphics card, the better, the best.
Anyways, bad timing for buying a PC. Third generation Ryzen processors, expected to be much better in performance per dollar and maximum performance are coming this summer, and this year are also coming the next 7nm AMD GPUs (not the Radeon VII "teaser card", the actual RX 6XX or whatever its name will be) which are probably going to be a huge improvement in performance per dollar and maximum performance for AMD cards. Additionally you will have much more options for a monitor with hardware video syncronization than getting a Nvidia card (G-Sync and top Freesync monitors for Nvidia cards, Freesync for any AMD).