True.this is a tough question IMO, generally I don't care much about sizes, most of the renders in the game already look good to me, but it could be a fun "toy" to play with depending on how extreme the changes are and how they are incorporated into the story, I might like Caleh or Goblin Daughter grow a pair, but I'd like a story component to the size change rather than a simple scene switch like we already have with the Imp.
Me personally I would go after the noticeable ones and make them “MORE” noticeable
Jenny, Victoria, the priestess, Magda, the Minotaur damn forgot so many names the lady in the Tower the Nordic Vampire they are all great candidates for increasing the size
As for lowering All I would say is why? Just stick with Mia, Beth elves (I personally wish they had bigger tits) and leave us the bigger ones.