The Scientologist, because they are fun to reverse the bullshit on. They are especially intimidated if you talk about art, because they never know anything about it; but it makes them know you didn't 'have to go alternative' and that their proselytizing will get them nowhere, because they won't bother you (nor will any other cult) if they think you are not lost and looking for 'a place to belong'.
I always want an aisle seat (in case somebody farts or has other odours), and a Scientologist has never even been able to get anywhere with me when I went into the World HQ on H'wood Blvd. and asked where the nearest Kinko's was. He told me and didn't even try to interest me in their wonderful e-meter. Of course, it is fair game to really make him shut up, because in your original choice, you say he is a Scientologist, which he would have to have told you. That would be obnoxious enough to begin with, as something unwanted, and I would immediately tell him I was not interested in Scientology. If he pushed it, I'd complain to da management, as in airline attendant.