I'm really not advocating for people to push out reams of AI drivel and not learn anything while doing it, but of these three groups which ones are likely to be the most effective?

The ability to easily edit in word processors surely atrophied people's ability to really reason out what they wanted to write before committing it to paper. Is it sad that these traits are less readily available in the human populace? Sure. Do we still use word processors anyway because of the tremendous benefits they have? Of course. Similar could be said for spellcheckers, tractors, calculators, power tools, etc.

With LLMs, it's so much quicker to access a tremendous breadth of information, as well as drill down and get a pretty good depth on a lot of things too. We lose some things by doing it this way, and it can certainly be very misused (usually in a fairly embarrassing way). We need to keep it human, but AI is here to stay and I think the benefits far exceed the "cognitive decline" as mentioned in this journal.