For value to performance its better to get the r5 3600x, your b450 mobo is already good enough for it(you don't need to upgrade to x570 unless you want future expandibility to a r9 3900x or 3950x with gen4 pcie speeds), you can also keep your 3400mhz ram unless you want that sweet spot for editing of 3600mhz cl16 but its not that significant tbh or have more ram to 32gb which is more than enough for anyone for more chrome tabs(god the ram tho) or for programs like adobe premiere and after effects which scale well, if you can get a good deal on a ssd or m.2 one either sata 3 or better yet nvme.