Which one is Best to use on base Absorplion, Fusion or Viral ?
All 3 are good on hunters as that helps against fury and herald attacks
The 2 that don't affect drones are good on railguns.
Overall the blue one is best because a good defensive platoon can stop all attacks even without turret support so you just need to let your heavy turrets survive to get damage out if your toon fails you.
Absorption seems helpful at max level on a high-health platform. Make sure you use a Reinforced or Armored platform type -- definitely not floating. In general though, they still won't last very long against a juggernaut or herald.