I'm in the enviable position of getting to see the inner workings of creating some of this stuff, and playing around with character concepts, but Liminals are one of my faves. I love Frankenstein, which obviously helps, but the sheer personal body horror of them is awful and amazing. To go straight at Promethean seems odd to me, like Sherlock fans who forget the original Conan Doyle works. Frankenstein is old old old stuff, and the mythos of stitched together and/or raised dead is even older.
Exigents, thus far in my mock-ups and so on, have been a lot of fun to plot out and create power structures for. Like Holden and John said in the podcast, they offer both expansions for players who don't mesh so well with existing Exalt types or who have a firm concept that requires a bunch of houseruling to work with existing splats, and as increased antagonist spreads for STs to play with. And it's certainly played out like that in the scenarios we've discussed in game terms. Or not even antagonists, just wrenches in the works.
Getimians I have less familiarity with, but the one John put in a game we were playing was really really fascinating, so there's that. The powerset is so fucking weird.
The advantage of them is that they are all super rare so if you don't wanna have 'em in your game, don't!
(I did like the Liminal who accidentally gave himself a plagued eye in the game we played, super gross and also terrifying given the plague's symptoms)
I would love love love to but sadly, unless I can combine it with a work trip and get a grant to cover some costs of travel, it isn't gonna happen next year.