Go with 3600mhz 2x18GB RAM Kit
Upgrade ur PSU to a 650-700W PSU
MSI B450 Tomahawk as your motherboard
Buy any sort of 500mb/s SSD, they are all good and from reputable brands always, unless you want M.2 then you should go for Samsung EVO's
Unless ur Monitor is 144hz already, u should buy a 144hz refresh rate monitor, i recomend aoc g2590fx
For GPU you can go with the Zotac Gaming GeForce RTX 2070 Mini 8GB GDDR6, it might be a little bit overbudget, but ur saving in another parts so you can afford 50$ extra,
For CPU definetely Ryzen 5 3600X
Buy 2 extra 120 or 140mm case fans, depending on your chassis
For peripherials you should find ones that you feel comfortable for you, since these are different for everyone, i personally recommend the Duck Mini 2 as keyboard and Glorious Model O as your mouse, and G430 Logitech as headsets