I have always loved "Why Don't We Do it in the Road" because of Paul's awesome vocals (low, and then falsetto).
I love this song because it's so unabashedly ridiculous and funny. "Yeah, let's do something naughty in the road, who cares!"
I also like:
"Yellow Submarine" because it's really adorable. It gets slapped with a "cheesy" label, but it's a great children's song.
"Ob-La-Di, Ob-La-Da" because it's simply fun and high-spirited. I also like hearing John (and George?) being weird and silly in the background.
"Tomorrow Never Knows"--well, I'm not sure if this is generally considered "bad", but I'm sure its strangeness turns a lot of listeners off. I just love the droning, bizarre sound of it.
"The Long and Winding Road", but it's only "bad" if it's the version with Phil Spector's overdone production. The stripped-down version is more breathtaking and beautiful, I think.
I'm sure there's more but I can't think of any at the moment.