What publicly traded companies benefit most from AI replacing engineers?

Probably any of the large tech companies? Engineers are the most expensive there since they get paid very well there. AI making engineers more efficient theoretically means they would need less of them.

But I don’t think AI will replace engineers, and definitely not anytime soon.

The company that benefits the most, would be the one who is savviest about understanding what Machine Learning (it's never really "AI") can do well, and what it cannot. Lots of companies will lose a lot of money attempting it, because they don't understand the technology, or more generally how to evaluate the usefulness of new technology, well enough to figure out what it can and cannot do well.

So, the companies that still have tech (usually founder) CEO's making decisions, or at least a CEO who listens to smart tech advisors, is the one that will actually benefit from machine learning. This used to be Google, but their tech founders left and their initial response to ChatGPT does not suggest the replacement still understands how to do this sort of thing. Picking the right company is akin to asking, "who is good at implementing new tech in a sensible way?" If you knew that, you should buy their stock regardless of your opinions on "AI".

I think it leads to disproportionately more software and code, if anything. Tons of internal projects that companies would love to do, but IBM and Accenture are eye wateringly expensive, making many not worth doing.

You still have people manually typing information between different files (i.e. both are on the computer) at banks. You still have insurance requests that require mailing due to a lack of a specific portal to handle things of that nature. You have all manner of simple stuff that companies don't want to build the skills to do in house, but currently contracting it out is too expensive.

So I vote IBM. They can offer cheaper services to fill all that with AI.