Sorry went on a trading spree earlier.
If budget/supply allows, I would go for
AMD R5 5600x, it was just released and has great performance. Pretty future proof if you ask me.
However if you are looking to stick to last year's line-up, I would choose
R5 3600x due to its multi-core performance compared to
Intel's i5 10400. Single performance is pretty much on par with Intel too.
If you go for R5 3600x, B450M MOBO would be more than enough as you won't be over-clocking and all that. Also to save a PCIE slot, just buy
MOBO with integrated wifi such as this.
https://www.gigabyte.com/Motherboard/B450M-DS3H-WIFI-rev-1x#kfBesides CPU, all the other looks fine, 600W 80 Plus Gold PSU should handle 3060 fairly easily.