This is entirely a single person's opinion.
The two VSCode tools I tried over the space of a few days are Cody AI and GitHub Copilot.
For the latter, I'm on the waitlist for the GitHub Copilot Chat part so have missed out on that. Took less than 24 hours on the waitlist to get access to the GitHub Copilot Chat feature. But just appears to be similar AI to what Cody AI offers.
General questions about e.g. sfdx asked in the chat window are usually helpful and provide a quicker answer than Googling.
On code generation, my general impression is that a lot of distracting noise is generated:
Feels like pair programming with someone who mistakenly thinks offering a rough guess is better than keeping quiet.
and while good on language syntax a lot of hints are needed to get anywhere near the desired business logic. And it is frustrating that metadata such as field definitions are unknown to the AI except for what it spots in existing code.
In my dreams, and in line with:
Copilot's primary job is to assist you, taking care of mundane or repetitive tasks
I'd like an AI solution that could do the tedious work such as "add a 30 character string field called Abc to Contact appending to the layout or flexi-page and adding that field to the permission sets and profiles that contain most of the Contact fields".
I will keep running Cody AI and see if I can get more value out of it.
If you have success with other tools, or your experience is different to mine, do post an answer here.