1. Out-of-the-box integrated sync with a dedicated default host: keepass has 8 different sync plugins, all with different levels of maintenance & UX, each for separate sync backends, all requiring separate 3rd party backend account setup
2. Consistent cross-device features & UX: Keepass has 3 browser plugins with varying levels of browser support (not sure if any have mobile support?)
On top of the above, Bitwarden is open source and allows self-hosted sync
1.) Redundancy. Can't get at my KeepassXC?, then I try Bitwarden. Can't get at my Bitwarden? Then I try KeepassXC. Can't get access to both? Then I'm screwed (but this is unlikely).
2.) Browser extension. I like to be able to login easily to sites using their extension.
3.) LOCKSS (Lots of copies keeps stuff safe). Having a cloud-based mirror of my login entries stored in Bitwarden is marginally better than solely relying on KeepassXC.
4.) Logging into KeepassXC is sometimes more complicated than logging into Bitwarden. I have a long seven word passphrase for KeepassXC, and use a keyfile which I have to 'hunt down' in the filesystem each time I go to access KeepassXC (I have disabled the ability to store the last used database & keyfile for security reasons). With Bitwarden I just open the app and if it's unlocked, I get quick access to everything.
1) I have my database replicated several places already. Cloud storage, mobile, FTP server, etc.
2) I don't use a browser extension on desktop, but I know there is one. On mobile the accessibility permissions allow it to suggest login information both in third party apps and in the browser. I've found it works fairly well. If you aren't able to open your database quickly it might not be as convenient.
3) This sounds the same as what I was considering for (1). Historical backups would be important for recovering from possible corruption, but I have not run into this yet for Keepass.
4) Understood. Bitwarden doesn't support keyfiles?
I have been close to splitting my Keepass DB up into several, but haven't pulled the trigger on that effort.
I'm a Keepass user since 2006 and never had a problem with them. My database is saved in OneDrive and always keep local copy in my system. If OneDrive is down, my local copy is always there for me.