I think it's a bit unfair to compare each teams accomplishments without some context. P3 had themes about facing death, P4 Friendship/Truth, P5 Rebelling from society, How groupthink affects us, and truth to an extent. Of course the stakes in each game is going to vary. And while each team does deal with world ending phenomenons they at least fit with their respective games.
(If you were to personally ask me, Nyx is by far the biggest threat because we'll....death is death.) but if I had to talk about each team altogether I think they each accomplished what the theme for that game was. Which is what a good game should do.
Scramble introduction to Joker and Sophie
The protagonist. A third-year high school student. After moving to Tokyo, he got wrapped up in a series of incidents involving psychotic breakdowns and awakened to his Persona abilities. He formed the Phantom Thieves of Hearts with his friends to reform the distorted hearts of rotten adults, and led a major case full of conspiracy to resolution. After the case was shut, he returned home, but visits Yongen-Jaya in Tokyo once again for summer vacation.
—Action
A dauntless all-rounder with a wide range of attack skills.
Code Name: Joker. He has high mobility and attack power, and unleashes quick, close-range attacks with his dagger. His ability to fight with a wide range of skills is his greatest weapon, and he can use attacks of various attributes depending on the combination.
-Skills
His initial Persona is Arsene. He specializes in Curse-type skills and can sweep up enemies with his sinister power. Additionally, Joker is the only member of the Phantom Thieves who can freely change Personas. His wide range of attack skills allows him to strike the enemy’s weak point.
A mysterious girl the Protagonist and others encounter in the other world version of Shibuya. She seems to have all but forgotten her memory, except for her goal to “become a good friend to humans.” She is often giddy and mysterious, but her goal to “become a good friend to humans” is genuine, and in order to accomplish that she works hard to support the Protagonist and company. She can fight with Shadows using abilities that resemble a Persona. She is a character full of mystery, including the reason why she is in that other world.
—Action
Rhythmically connect attacks to sweep up crowds of enemies.
Code Name: Sophie. In battle, her outfit extends and covers her head, and her hairstyle changes. She fights using yo-yos, allowing her to swiftly attack a wide range of enemies. For her gun attack, she uses a Blaster.
-Skills
Sophie fights using floating objects called Pithos, which are similar to a Persona. She uses techniques of the same property as Bless-type skills. And in addition to Healing-type skills that support her friends, she also has skills that can weaken enemies.
5 Royal western release date announcement in 12 days.
Pretty easy, since they're the only person on the list of suspects not to be dead, in jail, or a Social Link
Bewitching EyesI hadn't realised personally until I actually had to, to continue on to the good ending. And my reaction was the same as the characters, which was cool.
I have to admit, that was a big part of it. He was around so often but wasn't a social link.
Edited by deludedmusings on Nov 22nd 2019 at 4:00:08 AM
On the actual "decide the killer" scene, the game gives you a list of requirements that the killer had to have met, gives you a list of damn near every character in the game, and gives you three chances to get it right. The real killer isn't the only person on the list who checks all the appropriate boxes, but the vast majority of characters can be written off as not fitting the requirements given. When I went in blind for my first play-through, I didn't get the right answer on the first try, but I did on the second or third.
Really from Jupiter, but not an alien.

They killed gods and got two serial killers and a budding serial killer off the streets.
The legend has returned.