The best options for Raw elemental [Khora] are as follows in order (with or without riven):
1. [Magistar] Incarnon (with Magus Aggress): Edge of Justice (+100 base damage and 40% attack speed), Orokin Reach (+1.4 range), Critical Parallel (+16% cc/+1 CD)
2. [Sibear] Incarnon (with Magus Aggress): Master's Shatter (+20 base dmg), Resolute Force (+6s combo duration), Absolute Valor (+25% cc)
2. [Ceramic Dagger] Incarnon: Breacher's Opportunity (+120 base dmg and another +80 dmg on shield break), Orokin [Reach] (+1 range), Absolute Valor (+30% cc)
3. Kuva Shildeg (with Magus Aggress) 60% toxin progenitor
4. Skana Incarnon, Nami Solo Incarnon: with +CC evolution 4
5. Tenet Exec/Tenet Agendus with 60% toxin progenitor
6. All other weapons e.g Amphis (with riven)

With increasing disposition, a Lich/Sister melee with +60% toxin and a riven still beats Amphis with an equivalent riven.

Toxin Corpus version: https://overframe.gg/build/345034/