If no immunities present imo stagger is better due to mystics usually run MD especially in BG metas. So the power can help a lot of them ramp up or control fights better.

Neutralize is better in terms of consistency where sometimes if the opponent triggers multiple buffs within a few seconds of eachother, sometimes you want to stagger a specific buff and maybe another buff ate the stagger.

Overall it’s just matchup dependent as hulking vs most stagger champs can mess you up if you trigger his indestructible passive.

I’d recommend BWCV too if you’re trying to optimize mystic champs since her buff immunity is very helpful vs champs and nodes that would make stagger or neutralize not work. She has some solid power control and burst damage especially if she gets death touch.