You can count on aps lb how many people have Apotheosis title but i think there are already like 30 now. Basically every new golden lb title is only there 10 times (not counting tie breaks).
Midas touch is not rare, even now quite a few wear it. Sentinel was in a package for 30 plat but is very old so might some inactive players got it.
I guess gold titles are the rarest ones if u count the amount of titles given away overall and not how many people wear it.