I think my first favorite song waaasss...hmm. You know, I can't remember? I'll just stick with "My Heart Will Go On" by Celine Dion, since Titanic has always been my favorite movie. I listened to that soundtrack obsessively*.
First favorite Airplane song? Somebody To Love. It opened up the Jefferson Airplane door to me. And what a wonderful door that was opened, yes?
Though, before I discovered Airplane, I was in love with the Starship's "Tomorrow Doesn't Matter Tonight"...I still like that song, too.

* I still do, too.

Mayyybe I'm a wee nerd, yep?