Any progenitor element is fine.

If you use Rauta or manually build combo, swap Corrupt Charge for a 60/60 Elemental mod (e.g. Vicious Frost) ( NOT a puncture mod - this is because IPS on tenet weapons ignore the 60% progenitor bonus, so a 120% puncture mod is actually a 75% mod and a 90% puncture mod is actually 56%, worse than 60% elemental).

Best Rivens:
Damage , Element (any element), Initial Combo, harmless negative - THIS IS THE BEST POSSIBLE NON-COMBO RIVEN - slot over Augur Strike
Damage, Element, Element, harmless negative - THIS IS THE SECOND BEST for non-combo and the best for x12 combo - slot over Augur Strike
Damage, Element, Puncture, harmless negative