I'm looking to generate some new passwords for myself that are easy to remember, but hard to crack. By choosing a generation algorithm and generating one random password with it, I can be relatively confident of how hard to crack my password is. (I can calculate its entropy.)
If, instead, I keep generating passwords until I see one I like, the security of my password is (significantly?) less. Worse, because I can't analyze my own mind like I could analyze an algorithm, I don't even know how insecure my password might be. It should be better (in terms of security) to control myself and say, before the password is generated, "whatever password is generated is the one I will use". But it might not be as easy a password to remember as "correct horse battery staple". It's hard to predict what will be easy/hard to memorize, and it can vary a lot from person to person.
What about a happy medium, where I decide that I will generate exactly N (for example, 10) random passwords, and choose one of them? Would this be any worse than "1/N times" secure?