A favorite song... this is a toughie. I don't know that I have one favorite song. It all depends on my mood, and my favorites change as I learn new songs that speak to me in one way or another. And I am pretty much constantly singing, so I go through favorite songs like you wouldn't believe.
For example, right now I really like "Mean" by Taylor Swift, but it probably won't stay on the favorite list for a real long time.
As far back as I can remember, I've loved the song, "Ships" by Barry Manilow. First of all, it's by Barry freakin' Manilow!! How can you go wrong? But it's such a beautiful and sad song, and I can remember lying on our big comfy sectional couch downstairs and looking up at the top of the vaulted ceiling to where my parents had this really cool sailboat mobile that hung there and caught the light from several windows. I'd watch it turn, and the little dust molecules swirling around it in the sunbeams, and my Mom would be upstairs cleaning, and she'd have put on a Barry Manilow record (yes a record) and I would just listen. Even at 3 or 4 years old, I knew that this was sad song about a person who really didn't ever talk to his parents.
Another favorite is "How I Love You" by Keith Green. I first heard this song when I was about 5 years old and my Mom had bought his "Songs for the Shepherd" tape. We listened to it in the car all the time, and I was quite fond of the "Whoa-whoa-whoa's" in that song. We were driving to a party at my father's boss' house, and my sister and I were in the backseat, and I asked my parents where Keith Green got the words for his songs. My Mom answered, "He gets them from the Bible." I thought about it for a moment, and searching through all my Awana memorizations, I asked, "Where in the Bible are the Whoa-whoa-whoa's?" My parents laughed so hard that my father nearly drove off the road. And, come to think of it, they never did answer my question!