I'm a long-time user of 1Password. I love the service. I have family sharing with my wife and it makes everything a breeze. She is not technical at all, but having a shared vault and the ease of use from 1Password has made her using complex randomly generated 50-character passwords, a different one for each service.
I have considered trying out Apple Keychain. But from what I understand it has no way of having a shared family vault. And from what I've seen the Windows integration using the iCloud for Windows app looks terrible, just like all services Apple offers outside their own ecosystem. I use primarily Apple devices, we are heavily integrated within the Apple ecosystem. But both I and my wife have to utilise Windows in our professional lives so it can't be Apple only.
I don't think Keychain on macOS lets you autofill anything outside Safari either? I mostly use Firefox on macOS, having to manually go into Keychain in order to copy passwords would be a huge downgrade compared to having the 1Password extension in Firefox. 1Password also lets me save software license information, notes, and MFA codes. When logging into Macrumours, 1Passworld will autofill my username, password and my MFA authentication code automatically.
I don't think you can use Apple Keychain as an MFA generator for OTP/MFA?