Michalis is awesome. I've been using him since he was released, and he hasn't let me down yet. Even without the Hauteclere refinement he served me pretty well, and with it he hits like an absolute truck. His stats are pretty well set for a flying tank, and his default passive skills are decent enough; he just needs something like Quick Riposte for B (can also do Vantage in B and QR as the seal), Reposition/Swap for assist, and Bonfire or Ignis as his special (I prefer Ignis, personally) and he's good to go. For his A skill, Iote's Shield works fine if you want to keep his seal slot free or are on a budget; otherwise, if you have the budget, Distant Counter, Heavy Blade, some of the Stance skills (Fierce, Steady, or Sturdy are ideal), or Atk/Def Bond are all solid options (basically any enemy-phase skill, since that's how you'll mostly be using him).
Also his voice clips are great. "Don't push me!"