The Vees are all some flavor of awful but honestly I kind of want to explain why I personally think Vox is the worst one, even above Velvette and Valentino, so let me get into it.
(Also disclaimer, just because they're awful people doesn't mean they don't have qualities that make them beloved characters to others, I'm just not talking about those qualities because that's not the point of this post. I'm not here to criticize anyone who likes the characters either.)
I'll start with Velvette:
She actually has a lot of similarities to Vox. She, like him, has powers that revolve around mob mentality. And she's really obvious and impulsive about it to be honest, which I think is influenced by the fact that HER way of inducing mob mentality is by way of the internet. She's an influencer persona, she's surrounded by yes-men fans and can just direct them at anyone who disagrees or critisizes her online, so her in-person interactions kind of fall short when she doesn't have that backup.
She literally tried to get all the overlords to stand up and go to war against heaven with essentially NOTHING to bring to the table. All she said was it's POSSIBLE to kill angels, and expected them to immediately follow her lead into trying to fight back. She did absolutely no research into HOW the angel died or if a sinner was the one to even kill them— for all she knew it could have been another angel or even one of Hell's royalty, which is a completely different power class and would have rendered any sinner rebellion she inspired into a suicide mission. This was such an impulsive move by her that completely relied on the other overlords falling into a mob mentality that she's used to recieving online.
She's dangerous in the sense that she can inspire this mob mentality online and could probably actually do SEVERE damage with her influence, but she lacks some things that Vox has that would truly make her an extreme threat in this area. For one, unlike Vox, she can't actually hypnotize people. She has to rely COMPLETELY on her charm and wits to get people to essentially worship her and her opinion. Two, she lacks experience. Vox has been around for decades and knows better about what he needs to say to get people susceptible to his views. Vox literally grew up in a time of extreme propaganda and was one of the people spreading that propaganda on the television. Velvette is an internet celebrity, Vox was a war recruiter.
Seriously, her social skills outside her internet personality are abysmal, and that doesn't help her in getting people to do what she wants. She genuinely Does Not Care how much of a major bitch she comes off as, and while people love that persona online, they certainly don't in person. She couldn't even suck it up to make a fake apology to Carmilla in the name of manipulation, and had to be (condescendingly) forced into it.
I would also go more into her danger as a potioneer, but we actually don't have TOO much info on that as far as I'm aware, like I'm not even sure if Love Potion was developed by Valentino's venom/smoke or if it were her own creation replicating the effect or if Val's smoke is based on her recipe, etc etc, so for now I'm tabling that.
This man has the subtlety of a fucking brick. He is SO obviously dangerous, and that's what makes him a lesser threat. Because in comparison to the other two Vees, it is MUCH easier to predict Valentino. That isn't to say people don't fall for his BS at all, obviously people do, but Val's thing is that he specifically targets genuinely desperate souls.
Valentino knows how to prey on people who probably know, in some capacity, that they're in deep, deep shit. Anyone who aren't desperate and willing to take any hand that offers are a lot more work in trying to manipulate, so they aren't really in Valentino's purview. That's Velvette and Vox's job.
Now, let's be clear, Valentino is a SUPREMELY shitty person. He's a rapist, he beats the shit out of his souls publicly and without ANY shame or remorse, he is extremely emotionally abusive as seen from the ways he talks to Angel both in person and over the phone, and he is an unapologetically violent and possessive person who was ready to shoot down a guy and his whole family because Angel was flirting with him. The guy (poppet, construct, whatever the fuck he was) didn't even approach Angel to begin with.
So, yeah, Valentino is horrible, lmao. But he's not subtle. He has too much of a temper to really be quiet about how much of a piece of shit he is. He consistently has to be reeled in by Vox because of how bad he is at keeping a clean public image. Like, he fucking LICKED the Princess of Hell's arm as a greeting, and this was before he dropped his "approachable and reasonable" persona in front of her. He is BAD at public relations.
There is enough cracks in Valentino's image that I genuinely believe that without Vox and Velvette serving as his PR management, he would be nowhere near as much of a danger, because he wouldn't be able to fool as many people.
Vox, as previously stated, is similar to Velvette in that part of his power is his ability to inspire mob mentality. He's also similar to Valentino in that he's a sadistic, violent asshole who was canonically described as someone who gets off on others' pain. What separates him from Velvette is experience, and what separates him from BOTH Val and Vel is self-restraint.
Which, yeah, I know, restraint who?? Are we talking about the same person? Well, yeah, we are. Because the only reason we see Vox loose his absolute cool in canon is because of Alastor. That is Vox's weak point and it was shown VERY explicitly from the first episode he appeared that he is generally the level-headed one who has to sweep up the messes of his partners when he isn't half out of his mind over his object of obsession.
Seriously, even while Valentino was having an epic tantrum, throwing glasses and ripping apart Velvette's models, threatening to wreck his own image by going over to shoot up the hotel Angel's in, Vox stays generally calm and even deescalates Valentino's poorly thought out plans, giving him alternatives to bleed out that aggression.
Up until the point Valentino mentions Alastor, Vox was by FAR the most in-control person in the Vees. It was only after he knew Alastor was back did he go on to embarrass himself on air with a song battle that he lost rather spectacularly. And every one of his mistakes after the fact are quite literally only because Alastor lives rent free in his boxy television head, it's honestly pitiful. I'm dead serious, if Alastor hadn't intervened by allowing himself to be captured by Vox, it is very possible the Vees could have taken Heaven hostage at gunpoint.
When we remove Alastor from the equation, we get a cool and collected business man who's secretly a fucking cult leader that can hypnotize mass amount of people through their digital devices. We get a guy smart enough to portray a squeaky clean image on air, and be a violent sadistic abuser behind closed doors. We get a man who stalks people through cameras all over the damn pentagram, who TELEPORTS THROUGH TECHNOLOGY, who can manipulate people's views and opinions to suit his needs, who can take away your personal autonomy just by looking you in the eyes and make you FORGET it ever happened—
Vox is one SCARY motherfucker. Like for real, at least with Valentino and Velvette you'll KNOW what they're doing to you, or at least know what they could and would do. Vox can take everything he could ever want from you without you ever knowing that he's doing it.
And he would do it. He has absolutely proven that he would 100% use his entire arsenal of abilities and influence to absolutely wreck people. He beat up Angel and made him an unwitting spy, he made the entire population of sinners turn against Sera and Heaven in a deliberate strategy to gain their approval and further his own goals, he straight up hypnotizes people through TV displays to buy his company's products, we saw a whole sequence of Vox convincing some poor girl into signing away EVERYTHING and then discarding her the second he or his partners couldn't squeeze out anything else of value from her.
Vox is an ASSHOLE, and he's the scariest one because he's the best out of the three Vees at pretending to NOT be an asshole, up until it's too late for you to save yourself. And that's why I feel like he's the worst out of the three.
(This, of course, is not even mentioning the fact that's he's racist, extremely patronizing towards his partners, has internalized homophobia that shows in his interactions with Val, and is SUPREMELY entitled. Honestly I like him best when he's suffering and that's because he deserves it.)
(Seriously there's more to mention abt Vox and his attitude towards his partners but this got too long and my brain is getting fuzzy 😭)