Two sets of 2x8GB G.Skill Flare DDR4-3200 CL14, which I use. Once you hit 3200mhz the speed differences become almost negligible outside of benchmarks, basically in the margin of error, as shown by Techpowerup's memory scaling benchmark with the 3900X and different RAM speeds. G.Skill Flare is built for Ryzen, so it's guaranteed to work on every Socket AM4 motherboard at the rated speeds and timings. Actually thanks to AGESA improvements over the years, I'm actually able to get it at DDR4-3333 at the same timings and voltage
https://www.newegg.com/g-skill-16gb-288-pin-ddr4-sdram/p/N82E16820232530?Item=N82E16820232530&Description=g.skill flare&cm_re=g.skill_flare-_-20-232-530-_-Product
