Coil, Ultima and EX primals for me, since I got my first relic for coil, and since they came out for the ex primals. Anxiety and not wanting to waste other people's time (or my time) wiping is the main cause. Well, that and the lockout for coil, all my friends that I do normal stuff with have their own groups for it. Not so much upset, I was kinda hesitant about everything post-Praetorium at first, esp hm Garuda (ptsd from 1.x, was the hardest fight before the servers shut down barring Darnus hm and I never got to beat it), now I can solo tank it, it'll come eventually.
For coil I'd like a CT loot lockout, other stuff I just need to man up and do it. As for content I'd like, some actually challenging, thoughtful solo/duo stuff would be nice.

On the bright side, not having done everything keeps me from ever 'running out' of content, and keeps me looking forward to it.