This is such a tough question to answer. Mostly because I actually enjoy pop music, which means I'm always finding new songs.
I suppose, though, if I was sticking with classics, I would have to go with something from when I was a kid. Now, my favorite group as a child was - ahem - Menudo. (I'd have totally lied about that, but some of my readers know better and would have called me out.) Once I outgrew that stage, my favorites were hair metal and hard rock from the 80's and 90's. Kiss is one of my all time favorite bands, as is Bon Jovi. Any one of their songs could easily be a "favorite" of mine (except Wanted Dead or Alive - I never really liked that song, despite its overwhelming popularity).
But if I really had to pick a favorite song ever, it would probably be by an absolute favorite artist - so I'd have to say Simon and Garfunkel. I grew up on their music, because my dad is a huge fan. They have some really well-known songs - Bridge Over Troubled Water, Fifty Ways to Leave Your Lover, Sound of Silence, Khodachrome, The Boxer... The list goes on.
My favorite? A lesser-known tune called Song for the Asking. It's short and sweet with a pretty melody. It's a very simple song with simple lyrics - and a simple message.
I've always been pretty short and simple (never mind some of my long-winded posts). I'm not huge on detailed explanations - I'm a bottom-line kind of person. So short and sweet appeals to me.
Of course some things in life are complicated. But the things that really, truly matter - like love and friendship - should be simple. We should all be grateful for the people in our life. Those that are just passing through, and those that stay for a while - or forever. They're all important, and they're all a gift.
I've never understood why anyone would withold their love, or respect or friendship for another person. So for me, it's always been simple.
My love and friendship is there - all you have to do is ask.