(Firefox has a good security team, but Chrome's is unmatched.)

In terms of technical implementations, Chrome naturally surpasses everything else in a naïve myopic comparison (and always will), but holistically a secure algorithm isn't going to protect you if you've voluntarily handed the keys to the kingdom to umpteen untrusted parties. Chrome gets all the technical details right in a context where doing so seems redundant.

Secondly, that's a single step in the threat model; it's not just about what a Google engineer would do with your data, it's about attack surface area when any Googlers (or Google infra, or Google partner infra) that is compromised automatically exposes you.

The simple act of transmitting and storing your data to anyone, no matter how secure their systems are, is still by definition less secure than simply not transmitting that data.