Who should I give TA Raven set to?

RobinM with -spd has the best ivs for it. Together with sword/bow breaker and qr seal imo

And lyon is prety close thanks to his legendary tome

Lyon doesn't even need TA Raven to be good(he's already got a legendary Raven tome).

I would go with M!Robin, over F!Robin(she can be anti-Calvary).

M Robin or Lyon, both are great picks. F Robin does better as a Keen Gronnwolf+ +Eff Vantage unit, with Fury. That way she can survive Brave Lyn or Reinhardt, one-shot them, and then Vantage one-shot the other. Picking between Lyon and Robin depends on which color you're more in need of for Arena Assault help. I will say though that Lyon with TA and Naglfar can one-shot some Brave Lyns on player phase, so that's something to consider.