"Innocent" is actually one of my favorite Taylor songs, but perhaps it's mostly for personal reasons. When the song was released, it made me think of my brother who was actually 32 and who, despite being a good person deep down, took so many missteps in life that hurt other people and also sabotaged his own self. Everytime it seemed like he was getting his life together, he would fall by the wayside again, but no matter how many times he messed up, I couldn't help but love him and feel that he was just like the person Taylor was singing about, still just an innocent. He died from a drug overdose shortly after Speak Now was released, so whenever I hear "Innocent," I can't help but think of him and cry.
As for my least favorite Taylor song, it would have to be one of the songs off the debut's re-release. I thought all three were weak tracks. Otherwise I'd say "Today Was a Fairytale" because it felt like Taylor was doing a poor self-parody and taking a step in the wrong direction, though ultimately it didn't matter much.