Normal mode raids, and to a lesser degree extreme trials, I will do with pugs. The exception being if the extreme trial has trickier to execute mechanics, then I'll tend to avoid pugs.

Savage raids, I run with a static both because we're all about on the same page while learning, and because we tend to tweak the method of handling mechanics in a way that makes things slightly easier, but then also makes it harder to shift to a pug group if I want to clear them floors later (for example we do O8s first mode in a diamond pattern rather than a square).