Meta in a PVE
Jalter’s train is mainly cuz Highest ATK with a heavily offensive kit + Merlin. You literally can compare it to having a Hans + Shakespeare + Berserkers (even though it’s not as consistent and lags behind in damage. It follows the same lines)
Honestly though, I don’t see how break bars actually nerf or messess up Buster/Quick/Arts or whatever, it just negates one-shot strategies, which doesn’t seem like a nerf for any card.
Buster is still buster, so it’ll deal the most damage and that’s good. Now it’d be dumb to try and heavily burst in a single turn and not planning further than that beforehand.
The ideal would be dealing consistent damage over time either via buffed cards, crits or NP spamming if that’s possible, even DoT effects like Burns, curses or poison (which are a nice niche recently with Command Codes). You can also set up for a nuke, and that works regardless of the card type. Charmlock also exists (Depends on the quest gimmicks though), debuffing strategies (Asterios set-ups). There are tons of ways to do quests.
Now, if we talk about “Fastest and safest clear for CQs” then that’s something else that depends mainly on niches, abusing mechanics or high end team comps (Like double Skadi + Dantès).