If the motherboard will handle it I'd recomemend getting the latest tech so 9600K. You may want to wait until July for the AMD launch to see if Intel will drop their prices.
Don't let anyone talk you in to buying a brand or model you don't want. Buy want you want it's your money. I always feel when you go to turn your rig on you should have a smile on for face. You don't get that buying something you really didn't want because you were talked into it against your wishes.
That Haswell MB doesn't support the 9600K nor the memory so both would need to be replaced.
We try to recommend parts based on the best performance for the money, nothing is forced. Before my Ryzen 2600 build I started a budget build using the Gigabyte Z370 MB, 8gb DDR4 @2666 & a Pentium Gold G5400 as a placeholder for the 9600K when I had the extra money. As time went on I did more research between the CPU and cost of aftermarket cooling, overclocking, value & upgrade-ability and it turns out I made a mistake as I don't game at a high refresh rate and could use that money to better other parts of my system. Eventually sold the parts to my friends kids as a homework/gaming system.
https://pcpartpicker.com/b/6Fr6Mp
Changed mine to the 2600 and never been happier but then again I'd rather play at a higher resolution around 75hz so the choice was well made. Since EyesofJack is playing at 1080P/60hz the Ryzen would be a good choice but if at 144hz+ then I would of suggestion Intel as the performance per core post overclock would be needed to maintain those high FPS.