DDR4-3200 is a good choice.

Prolly some Corsair or gskill 6000mhz cl30s - 32 gig for standard game reqs while goofing off. Are you doing more than gaming?

https://benzhaomin.github.io/bdiefinder/

since you have ddr4, use the b-die finder. ddr4 availability isn’t great, so i would try to find a 4000cl16, or 3600cl14-16. this is a good 32gb set for the money. ddr4 is a good deal more expensive than ddr5 now unfortunately, that kit is by far the cheapest fast 32gb kit i can find. if you want to go with only 16gb though kits are easier to find.

Use DDR7 ram it’ll be fine.