Between those two, I would go with regular Debian, or Mint LMDE if it has to be one of the two.
Debian is much better about providing a reasonably updated desktop experience these days.
As for Ubuntu… Their engineering is bad, and they’re shady. They push their solutions over standard stuff, and their solutions are conveniently setup to allow them to close source the code if anything ever reaches wide adoption or are proprietary from the beginning.
Indeed. It seems that everyone dislikes sysv, but a small group can’t decide on what the better option is.