For me (as an engineering manager these days) the most important quality I look for in a developer is a people-focused approach to work. No matter what you work on you should always be thinking "How is this making the end user's life better?" even if your code is miles from anything thr user sees. That manifests in traits like a focus on being error free, fast, usable, accessible, ethical, and 'kind'.

Good developers don't stop at making the happy path work. They obsess over making their code fail elegantly. They make systems that are strongly robust. They think about the failure states deeply. Slightly antagonistcally, they're also able to prioritize moving forwards when something is good enough rather than trying to make something perfect.

In my career I've only met and worked with a handful of really good devs. I've worked with loads of people who are great at one or two aspects of the job, but you rarely find the complete package. I think the best devs have a key skill of understanding how to make good tradeoffs and maintain a balance of what's needed versus what's interesting. I know I don't have that skill (yet).