Which is the best element for one-shot AOE?

[Iceflame3029]

I recently did some experiments in the Simulacrum.

Weapon: Aeolak with Serration, Point Strike, Vital Sense, Galv. Chamber (rank 5), Galv. Aptitude (rank 5), two 60/60 mods and Terminal Velocity

Warframe: Gauss Prime (no ability used, only Corrosive Projection as aura)

Companion: Panzer Vulpaphyla (without priming, only bond mods for fire rate & crit damage)

Enemy: Grineer Heavy gunner 

For lvl < 50, gas deals the most damage with 1 alt fire shot, even better than corrosive which Grineer is weak against.

For higher lvl however, no element can one-shot enemies. Maybe I’ll try viral + slash from Hunter Munition or just get the enemies primed.