there's about a 10 euro difference between an atx b450 mobo and a b460 here (then again, a 'desirable b460 would probably be even more)
No one mention that B460 board will only allow you to run the any RAM kit you buy at a MAX DDR4 2666MHz (I can't believe Intel is still doing that kind of stupid market segmentation, at least if you are lucky with stocks there are a few very decent Z490 boards for a fair budget).
And as such whatever small performance diference between the chips will be gone. You need to get a Z490 board to be able to run memory at over DDR4 2666MHz.
If you go with the B460 then both chips will be basically identical, been the Ryzen 5 3600 a tiny bit (very few FPS) faster depending on the game.
In any case, whatever you pick both chips are very good to game.
For future upgrade path, I would really skip both B450 and B460 chipsets and get a B550/X570 or Z490. Sadly at this point is really hard to get most decent motherboard at a fair price.
Edited: as it was mention by others already, yeah don't waste your time with OC the R5 3600, but do get a decent cooler for it to allow the CPU to keep the boost frecuency for longer... as long as the you have a decent motherboard and airflow inside the case (which are both good things to have for either Intel or AMD).
Sources:
View: https://www.youtube.com/watch?v=NqCGHHOZYcA
View: https://www.youtube.com/watch?v=csFwlKgZCzM
Good luck