The problem with PGP is that friction is in every message you send. For every email you have to make the decision about encrypting the message and entering your passphrase. It's a hassle.

The reason I recommend Bitmessage is because after overcoming the friction of installing it, it's frictionless. You don't have to remember passphrases or anything. It also has advantages over PGP-encrypted email like deniability, built-in spam minimization, broadcast messages (like Twitter), chan boards, etc.