Rihaku
The Internet
If nameless wasn't kind of a spoiled shit, I'd pick incarnation in a hearbeat.
But he is a spoiled shit, and his zanpakuto-analogue is probably going to be unrelentingly horrible to deal with.
Nameless is quite charming and socially adroit... he talked a lich into giving up its vengeance. He subordinated Suizhen and won over Xiaoling.
@Rihaku
If Elysium exists, are we objectively making the Multiverse a better place by culling the Elder Horrors of Reality? Or is the Vault creating them like the Monsters in Jotunheim?
Possibly, you don't know for sure. A finite reduction of such creatures may not be particularly relevant even if it is occurring.
It's interesting that the natives of both options have difficulty surviving outside their realm. Hints that, perhaps out True Realm is not so True. Perhaps a function of their Accessibility score.
Could you survive in a realm with different physics? Few have the power or the patrons to manage such a feat.