When I did some research on hardware keys I was between Yubikey and Nitrokey. I ended up going with Yubikey because KeepassXC supported it.
Something to keep in mind is purchasing a backup key. I bought one for my wife and we use each other’s as a backup.
For KeepassXC it does not support registering multiple keys (at least not that I have figured out), so I have a copy of my database where it uses my wife’s key as a backup.