The fact that I can't easily use a Yubikey for 2FA with KeePass has always made it a nonstarter for me. After experiencing the comfort and peace of mind I get with "master password PLUS Yubikey" in Bitwarden and LastPass, I could never go back to just having a master password that could be keylogged.
Yes, you can have a static "keyfile" on a USB stick that you use for 2FA, but that could be easily copied. "But if they have physical access it's already game over!" The scenario I am concerned about is unlocking my master database on a computer I don't own, like at work. I can do that with Bitwarden.
Bitwarden is closer to a LastPass competitor in the sense that it combines the encrypted database management with cloud storage, so that you can trivially share the database across devices.
Keepass is only the encrypted database management component. If you want to share that database across multiple devices you have to combine it with a cloud storage service (DropBox, Google Drive, OneDrive, iCloud, etc).
The major advantage of Keepass is that hypothetically it could be a completely off-line system, you could manually copy the database via e.g. USB Stick to every device if you so wished.
Keepass2 does not perform any syncing between devices (as far as I know), it's "just" a password safe that stores data in an XML file.
Personally I sync my Keepass files using a secure file sync app (not Dropbox), which is sufficient for me. I don't log into account on my phone so I don't need the passwords there, I guess it can be a reason for people to use Bitwarden.
Yes, you can have a static "keyfile" on a USB stick that you use for 2FA, but that could be easily copied. "But if they have physical access it's already game over!" The scenario I am concerned about is unlocking my master database on a computer I don't own, like at work. I can do that with Bitwarden.