RSA and DSA (Digital Signature Algorithm) are methods of encryption for generating and authenticating public keys. They are both equally secure, but DSA is faster for generating key, but slower at validation. Meaning: it will take longer to login to a server.
Ultimately, regardless of which method you use, generating keys only takes a couple seconds and you only have to do it once. Whereas, logging into a server is something you may do repeatedly throughout the day and even second spend waiting can be aggravating. (Much like how it's annoying waiting for your phone or TV to boot up everytime you turn them on.)