While there are missing features (e.g. ability to merge records), I have to say that Passwords.app is worlds ahead of 1Password since their electron rewrite. System Settings is not the best (mostly because the search is broken), but Passwords is sufficiently good that I haven't bothered looking what it's written using, whereas I can immediately tell with Electron.

System Settings is so slow for the amount of contents it has that I have to say it is probably the worst offender per content capita

Hard agree on 1Password. After Slack it's probably the worst Electron app on my Mac.