What are the best b-sides/rarities?

The amount of great tracks by Bowie that didn't even make it onto one of his studio albums is pretty mind-blowing...

On top of the classics he gave other artists to cover (All The Young Dudes etc), he's got all these b-sides I never knew about until recently!

What are some of y'alls favorites in this category? My buddy was showing me the Young Americans era version of "John I'm Only Dancing and that rocks. "Crystal Japan" totally could have been included on the Heroes album (though recorded in 1980, I know)...

We talked about it for a podcast, if anyone's curious: https://open.spotify.com/episode/0CkjilM6JYsQUWE3ehflmx?si=c281399e00af478f