Not a fan of QTEs in a turn-based game. I should be able to leave to go make a snack and return without having missed anything. Also there's really not enough time to react to anything. You'll have a fraction of a second to decide if you want to take an AoO on an enemy that's running away, decide to riposte an enemy attack, or figure out if an enemy is actually targeting your wizard with a ranged attack and then also if you want to Shield it.
Also, how would the game know what character you want to take a reaction and which reaction to use? Do you have to also select the character&reaction before pressing spacebar? This seems difficult with the way the camera jumps around during combat.
OP I've seen a similar suggestion to yours where the game briefly slows down when a reaction is possible, and a pop-up appears asking "Do you want to take reaction X?" This allows more time for the player to respond (a few seconds), doesn't require the player to determine which reaction is applicable and select the appropriate character, and doesn't bring the game to a halt. This seems more player-friendly and I'd prefer it over what we have now, but I'd prefer a combo of un-timed pop-ups and toggles determining which reactions can prompt pop-ups even more.
As always, multiple options to accommodate different playstyles is best.
