Me (sorcerer)
Lae'zel
Shadowheart
Astarion or hireling (if they're not as shit as it currently seems they might be)
is probably what I'll be going with. Though I might swap Lae'zel for Karlach now and then depending how much they actually interject in dialogue. I think an arcane caster isn't necessarily mandatory, but my character happens to be one anyway.