hi, i was juz browsing and stumbled into you post, and i was in you sheos before. hahahaha
your final distro choice depends on your linux skill and what u r using it for
nevertheless, for your choices, i think you should read "Lightweight Linux distribution" on wikipedia
no offence guys, but anything fork from ubuntu would fill the hdd from a basic setup
not much hdd space for anything else
my personal choice is slitaz, extremely light, 30mb image file and and install space of less than 512mb
my was 200++ mb, leaving rooms for other things. apps are edequate for basic offce suite and webrowsing
puppy linux would be my second choice.
lastly if you really know your ways around linux CLI(command line interface), use a debian and build it your self wif any packages u need.
then again i dont know what u use it for nor your linux skill
but, good luck and pay it forward
p.s. wikipedia link i posted is a gud place to start
i would also recommend trying on a live usb first, and see if it fits your needs