I know the Op said 1 of each, I'll allow myself to post 2 of each of though:
This The Smiths cover by Low, as my sad song:
Or this Coil song, one of my all time favorite songs:
And this Dinosaur Jr, song, which also happens to be one of my all time favorite songs, upbeat while not exactly happy:
Or this Syd Barrett song, which is definitely on the happier side of things:
So many great ones by Syd, it could have been Octopus, No Good Trying or even Wolfpack or from his time with Pink Floyd Bike, for a sad song by Syd definitely Dominoes!