The book Practical Cryptography With Go suggests that ED25519 keys are more secure and performant than RSA keys.
If you use an RSA keys for SSHkey ... that you userecommends a key size of at least 2048 bits.
the ED25519 key is better
ssh-keygen -t ed25519 -C "<comment>"
If rsa is used, the minimum size is 2048 But it is better to use size 4096:
ssh-keygen -o -t rsa -b 4096 -C "[email protected]"
ED25519 already encrypts keys to the more secure OpenSSH format.