So how many different paths are there now?
I remember the story/characters were slightly different depending on the lair chosen.
I personally do not want to give up any of the concubines, I don't like dig girls, nor do I want any concubines corrupted at all by someone else.
So knowing this, which lair would be best?
I would recommend the Spire. Nothing is more dragon-y than living in a old, abandoned spire. Plus, you get the Warlock Malagar, who's a real bro. The only potential concubine you would have to give up is Valzira, who's part of his quest-line of having his revenge on her.
Depending on the mode you are playing, either power- or dark-fantasy, you don't necessarily have to give up your concubines. In power-mode you automatically pass all skill-checks. No need to eat or give up any concubines. In dark-fantasy you'll have to make certain decisions in order to level up your skills and pass the checks, like eating or whoring out certain characters.
Regarding the corruption part, there's no clear corruption in it. The closest we get to corruption is Zyzerix turning Heloise into a Succubus. Zyz herself being a futa-succubus.