I feel like some of the discussion about AI is sleeping on Dai V, here. If you're only expecting to need to break Excalibur then Atman is obviously better. Dai V has some nice benefits, though.
Vs. a CI deck, where you might need to break Mother Goddess, Excalibur, and now Loki, it is very effective. It's the only breaker you need so cost is less of an issue. It is relatively inexpensive to break all of those things, as an AI, assuming you have at least one Cloak out.
It can save you a decent amount vs. NEXT Silver once there are three+ NEXT rezzed if you are otherwise using Blackstone (though if you have Corroder that's probably more cost effective in the short term to be worth it).
It acts as a wonderful backup breaker against Skorpios.
It laughs at Komainu and Tour Guide, which otherwise ruin Dagger's day (though Switchblade handles them better).
Atman isn't the only choice here, is what i'ma saying.