You're not alone :-) I asked a very similar question about a month ago: https://news.ycombinator.com/item?id=42552653 and have continued researching since.
My takeaway was that autocomplete, boiler plate, and one-off scripts are the main use cases. To use an analogy, I think the code assistants are more like an upgrade from handsaw to power tools and less like hiring a carpenter. (Which is not what the hype engine will claim).
For me, only the one-off script (write-only code) use-case is useful. I've had the best results on this with Claude.
Emacs abbrevs/snippets (+ choice of language) virtually eliminate the boiler plate problem, so I don't have a use for assistants there.
For autocomplete, I find that LSP completion engines provide 95% of the value for 1% of the latency. Physically typing the code is a small % of my time/energy, so the value is more about getting the right names, argument order, and other fiddly details I may not remember exactly. But I find, that LSP-powered autocomplete and tooltips largely solve those challenges.