Should I be forgoing survivability mods for ability enhancements on Vauban? The first thing I noticed when starting him was how low his defenses seemed so I gave him some pumped up health/shield mods to try and make up for that. But that meant I didn't have the capacity to support buffing his skills. Ironically I only have issues with him in defenses because he has no way to clear the field like Ember and Frost who I play as most frequently. For grinding survivals though I can just run around slicing things like on any other frame while tossing in the occasional vortex when there's too many.
Also I don't really do raids yet, and don't even know what LoR means. I've only been playing for a month and most of it's been grinding for mastery ranks.
Ah, well then thats my fault for not asking how far you are into the game yet.
Well, I can at least tell you that I really don't put much into building survivability by directly modding for health, shields, and armor. His base armor stat is super low and most caster type frames don't get much out of buffing it. I essentially survive by not letting them attack at all so I buffed his power, power efficiency, power range, power strength, and power duration. Lets me keep as much stuff on the battlefield as long as possible and covers as much area as poosible and allows me to cast repeatedly thanks to my increased power pool and lower cast costs. Whatever mod space that was left went to a health mod (Vitality) since out of the 3 defensive stats, in vauban's case the vitality would get the most mileage out of it because of his miniscule armor value. Shields are unreliable as they are completely independant of the armor value and several types of damage can simply wipe them out or damage your health pool by ignoring the shields altogether.
I would also say if you havent already done so, complete all the quests up to the second dream and you can further increase your survivability with all frames that way too with that quest's reward.