Astarion - always. Easily my favorite companion so far.

Shadowheart + Lae’zel - most of the time. I switch one of them for Gale sometimes.

I would like to bring Gale more often but it’s so hard to keep him alive.
Enemies always favor him, even if he’s miles away - party positioning be damned. It’s annoying.

Wyll - never. He seems nice enough but I find him a bit boring. His Hero act doesn’t impress me in the slightest and his story in general is the least interesting for me, at least for now.