I have a lot of experience with both. As a tech savvy user, I slightly prefer KeePass. Syncing between devices is slightly more painful, but I find it to be more reliable, and it doesn't have the attack surface that Bitwarden does. (While encrypted, Bitwarden still really wants a web server and a local database connection.)

VaultWarden is probably better for those who can't be bothered to move a file around and want direct browser integration. With KeePass when you need a password, you'll make sure the username has focus and then alt+tab to KeePass and hit "autofill". Some sites won't take "username{tab}password{enter}" and you'll have to customize the configuration.

VaultWarden is better at prompting you to add new passwords. I prefer the workflow that's encouraged by KeePass, where you open the app first and use the app to open the URL. (You can do this in VaultWarden too, but it's less obvious.)