I'll start! The first song I listened to by Yes was "A Venture!" A little side lore: I was into Rush before I got into Yes, and when I heard Geddy (I think) say that he would go see Yes in concert I thought "Why don't I check them out!" And now I am a big Yes fan :)
The song that made me really get into Yes was Onward though. I was legit sobbing and blown away! Please put a link to the songs! I really wanna hear your faves :)(because I don't remember what every Yes song sounds like lol)