personally I am making
Edelgard-Monk and then branching off to either priest or mage, mage because she gains a skill I think from reason, and priest because it's ironic seeing as she's all like the crests are to blame, and faith is her weakness, suboptimal, yes! ironic, maybe.
Dimitri-Cavalier it just fits him like a glove he is good with riding and as far as I am concerned cavs rock
Claude-some level of Archer and if given the option bow flier.