TOS DVDs, purchased in the original 2-episode per disk format sold one disk at a time.
TOS Blu-Ray. Hated to rebuy it after spendng, what, $600 for the DVDs. But I had to do it. Thankfully it wasn't TOO expensive.
TAS DVD set.
TNG DVD set. Definitely NOT worth rebuying on Blu Ray to me.
Best of Both Worlds blu-Ray. What the hell.
Oh - I also have it on laserdisc!
DS9 - buying it one season at a time and rewatching. Up to S6 now.
That's it. I have no interest in V'Ger or Boobyprise on disk.
I also have all of New Voyages/Phase II burned to DVD.