How would you sort Barty Crouch Jr? Also, I've seen a lot of different sortings for Voldemort, what do you sort him as?
There is a two-part sorting system I like to use when I do this: I sort both their Motive [Primary] and their Method ['Secondary.'] More detail on the system I'm using. Lets get into it:
SECONDARY (METHOD)
Voldemort and Barty both feel like loud Bird secondaries (probably why they work so well together.) I don't know who came up with the Triwizard Cup plan, or if they came up with it together - either way, it's a patient plan, with a lot of steps, that takes a whole year to carry out. Voldemort seems to like that sort of thing. He likes planning, he likes contingency plans, he likes setting up dominos for a while before knocking them over.
Although... Barty is such a loud Snake primary (I'll get to it) - that it's possible he's modeling a Bird secondary to please Voldemort, and underneath he's something more Improvisational (Snake or Lion). He's very comfortable making things up on the fly - everything at the Cup was spur-of-the-moment, the dustbin thing was something he came up with on the spot in order to throw off Arthur Weasley, and at the end of Book 4 he still nearly manages to kill Harry after the plan goes sideways. I also think it's interesting how comfortable Barty is being Moody, and Moody is a loud Lion secondary - honest, direct, comfortable with trusting his own power and quick thinking to solve problems. Also, nothing that Barty says as Moody is a lie. He uses very specific phrasing, but it's all stuff he authentically believes. (ie - "If there's one thing I hate, it's a Death Eater who walked free.") I think that the Imperius curse would be an especially horrible punishment for someone whose power comes from their own authenticity. Yeah, I like that. Lion secondary Barty Junior.
(He can still model one hell of an Actor Bird though - both as Moody, during his court performance, and escaping Azkaban disguised as his mother. But I don't think he likes to. The happiest and most joyful we ever see him is when he's just laying out the truth.)
But Voldemort... when things things don't go according to plan he does have trouble pivoting quickly, and will definitely make a "No! This cannot be!" kind of speech. That's very Bird Secondary. He also loves collecting shinies, tools, knowledge, and skills. You're never quite sure what the extent of his power is - he might just start flying unsupported, or somehow know that you were talking about him behind his back. That must be very stressful for his Death Eaters. And while he exists at the center of a group, Voldemort's power doesn't come from the group. It comes from his knowledge, skills, and - when he was younger - the ability to play a part extremely well. Deserving, subservient, charming good boy "Tom Riddle" is definitely one of Voldemort's Actor Bird personas. (Birds often like to give their personas distinct names.) The angst of getting "stuck" in a persona is also a very Bird thing - and this definitely seems to be the case for Voldemort. There is a kind of resentment that he still has to *be* this person during the scene with Hepzibah Smith - and a relief during the conversation with Dumbledore when he doesn't have to be "Tom" anymore.
PRIMARY (MOTIVE)
Like I said up top, Barty is a LOUD Snake primary. His "Master" is everything - some combination of a soulmate, savior, and father. And it really is about Voldemort the person. I don't think Barty cares about the politics at all. If Voldemort wanted to switch it up and start killing people with glasses instead of muggleborns, I'm not sure Barty would notice. When he talks about his motivations, it's always about - serving Voldemort, finding Voldemort, seeing Voldemort, all the people who don't deserve Voldemort. Before he met Voldemort his Person was probably his mother. Snake, all the way down.
Voldemort... is harder, because I do think the glimpses we get of his interiority can be interpreted a couple different ways. I do think he is primarily motivated by fear - he's afraid of ever being powerless or weak again, the way I'm sure he was as a small orphan child. This is where he gets his fear of death (the most extreme form of weakness and powerlessness) and also where his interesting relationship with his body comes from. I think he conceptualizes the "muggle" half of himself as the "weak" half (see his slightly odd childhood hypothesis that "My mother can’t have been magic, or she wouldn’t have died.") I don't think it's a coincidence that all his experiments to make himself immortal also make him look like a being that could only be magical (and nothing like his muggle father.)
Being motivated by fear is generally a sign that your Primary is Burnt, so what is going on underneath? I don't think Voldemort is an Idealist - his hatred of muggles is authentic, but it's got nothing to do with his official position that muggleborns "steal magic" or whatever. He knows that's ridiculous, but it's a talking point that will go over well with the purebloods. If anything, his main projects (taking over the Ministry, killing Harry) are just very extreme coping mechanisms. He never has to feel powerless again if he RULES THE WORLD.
So okay. What does he seem to enjoy. Voldemort IS interested in family history, family legacy, and heirlooms... which could possibly be a sign of a Badger primary. Only, he keeps those things to himself. If he were a Badger I would expect the fact that he's the Heir of Slytherin and the last of the Gaunts to be his platform. Snake is much more likely - a lot of Burnt Snakes will also focus intensely on their body when it doesn't feel safe enough to let an Important Person into their life (Hedonist Snakes.) Voldemort's doing an unusual version of that sure, but it absolutely counts. He's also only interested in his Death Eaters as individuals, not as a community. They are spokes of a wheel with him in the middle, and he likes it that way.
Sometimes it almost feels like Voldemort is running tryouts - looking for an Important Person he can actually trust. Ideally, this is someone he can see as his equal... but who is also so insanely loyal and subservient they might as well be an extension of his own body. I call this the Logan Roy paradox, because these two traits are... contradictory. It's kind of a weird sentence, but I think that Logan Roy of Succession and Lord Voldemort have extremely similar Primaries (and extremely similar backstories...) They are Burnt and Exploded Snakes who want people, but are terrified to actually trust them. So instead, they come up with ways to own them.
Both Logan and Voldemort pick (and cycle through...) favorites. It's not totally clear what makes Voldemort go from Barty, to Lucius, to Bellatrix, to Snape, to Draco. Part of it has to do with their performance sure, but Bellatrix is definitely defensive during the Unbreakable Vow scene. She doesn't like that she's not the only one in the loop, and she doesn't like that Snape is insinuating that he is more useful to Voldemort. I get the impression that somehow - the shine's worn off a little, and Bellatrix is extremely motivated to get that emotional closeness she had with Voldemort back.
(In Succession, Logan cycles to a new person whenever his current favorite starts seeing him as too human, or too weak.)
I think this quote about Logan equally applies to Voldemort: "He never saw anything he loved that he didn't want to kick it just to see if it would still come back." Voldemort enjoys makes making his Death Eaters grovel for forgiveness at his feet, he likes torturing them, making Bellatrix cry and scramble for ground by talking about her sister, or her werewolf nephew-in-law. Voldemort talks Barty up in a way that seems designed to make the other Death Eaters resent him, and of course takes Lucius' wand, and sets up an elaborate suicide mission for Draco.
And then there's the way he brands his people with the Dark Mark, symbolically 'owning' them while also making it literally impossible for them to leave. This is actually a really nice way of using a fantasy metaphor to get across how unhealthy Snakes work.
There's also something weird going on with the horcruxes. If I'm right, and the core of Voldemort is he wants someone who who he can respect, but who will also never leave him... then grafting part of his soul onto them kind of solves that problem. They're carrying around part of his power, so he can respect them. But there's also no way they can get rid of their new psychic connection to him, other than dying. So he is able to trust (love) Nagini. And... I did not expect to be writing a Tomarry thing when I started this, but like. I see it. At his moment of triumph, Voldemort creates the one thing he (subconsciously) wants: an equal who he is able to control. It's honestly very Palpatine. When you think about it, Vader is also the solution of paradox: an apprentice powerful enough for Palpatine to respect, but who will also never betray him.
tl;dr
Barty Crouch Jr ~ Snake Primary / Lion secondary (Bird model that he built for Voldemort)
Tom "Lord Voldemort" Riddle ~ Burnt and Exploded Snake Primary / Bird secondary