You'd be wrong thinking normal dmg is the most common in t3, but you're right for the rest. But, pending on your Gun UVs and if you're using a swiftstrike, I would choose Nameless or a combination of Nameless and Shadowsun. And, if you're allready at Atk Speed Ultra/Maximum, a combination of shadowsun and divine/chaos. I say Shadowsun instead of chaos at first because, from experience, I get hit far more often from piercing attacks when I keep my distance (slime family, needle shots, earth spikes etc) then shadow one's (cat bullets etc). On the second choice I would rather choose divine then chaos to keep elemental def somewhere and still having a dmg bonus medium against Fiends. But it is ofc always better to have some back up gear to better adapt to stratuses.

Would be my modest opinion on it