sm453 or lower, those are the D220 flux bins, which have a much nicer tint. The farther apart in tint the emitters you use for the mix, the lower the duv/rosier the light.
If you want to stick around 5000K you could still mix some sm573 and sm653 with a much lower temp and get way better tint than just sm503 or 573 on their own.
Clemence has a huge collection of E21A temp and tint comparisons here: [Reference] Nichia E17A/E21A (2000K - 6500K, R9050/R9080, color) CCT and tint shots