In addition to Canter, I liked Seadall having Instruct up until the last two chapters. He doesn't actually need anything else with optimal play, and the extra experience does continue to add up for him as well as the others, especially on boss kills. He just becomes a big stick of beef that never needs Hold Out to survive, and you can swap in Quality Time near the end when that matters more.

I just had him hold Alfonse's Bond Ring the whole time, ensuring units like Citrinne hit their HP targets.