If you are mk you say "all of them." But, we know better.
Best: This could change on any given day, but I love "I Will." I sing it to my kids all the time. It was the first song they heard when born.
Worst: I loathe Obla-Di Obla-Da. Can't stand listening to it.
Interestingly, both are Paul songs and both off of the polarizing White Album.
What are your picks for the best and worst?