Unlike Ultra Instinct, Ultra Ego can be tapped into easily by the user once they awaken it completely. As seen during the Tournament of Power, Goku struggled to do that with his ability, and it wasn't until much later in the manga that he finally mastered it.
Goku has already used Ultra Instinct while using the Super Saiyan God transformation, so using it on top of powerups is already canonically possible. Despite being opposites, Ultra Ego and Ultra Instinct complement each other perfectly.
Furthermore, in the only current relevant comparison, Ultra Ego Vegeta seemed to damage Granolah more than Ultra Instinct Goku. With all the evidence and inferences fans have available currently, it seems like Ultra Ego wins out in the strength department.
Wagamama no Gokui
Ultra Ego ( 我儘 わがまま の 極意 ごくい , Wagamama no Goku'i, lit. "The Secret of the Self-indulgent") is a highly advanced battle technique, primarily used by Gods of Destruction. It can also be manifested through the Ultra Ego transformation by those who are trained in the ways of Destroyers.
ultra ego is a form that takes beating, get massive zenkais, and then beat them even harder. ultra instinct is a form that is primarily used to avoid all forms of damage, or perfectly react to each move an opponent can do and counter them if possible.
As the Omni-King of the Multiverse, Zeno currently serves as the single highest benchmark of power in Dragon Ball Super. Being able to erase entire universes with a wave of one's hand is a level of power simply too great for Ultra Ego Vegeta to overcome.
Characters such as Beerus can make use of this ability, but Vegeta is the only one who has access to the transformation of Ultra Ego.
Vegeta's power level in his Ultra Ego form is a mere 4.5 quadrillion, while the Grand Priest's power level is at a whopping 100 octillion.
A final and most likely scenario is that there's simply nothing after Ultra Instinct. Goku will eventually learn Autonomous Ultra Instinct, and this will be his most powerful form through the rest of Dragon Ball.
Ultra Ego is a state that feeds on aggression and a desire to fight and destroy. In Vegeta's case, it brings him back to his evil roots. Ultra Ego builds upon the user's rage, which means that any calm on their part will break this heightened state.
Goku's final form is his True Ultra-Instinct form which was initially introduced in Chapter 85 of Dragon Ball Super Manga ''To Each His Own Answer''.
Vegeta was able to put up a decent fight against Jiren during the Tournament of Power, and he even defeated Toppo, a God of Destruction candidate. Unfortunately, Vegeta's level is defined below that of Broly's, and no matter how strong Vegeta is right now, he will end up getting crushed.
While fans will debate whether Vegito or Gogeta is stronger, they are both exceptionally powerful. However, both Fusion methods have specific requirements and drawbacks that make them incompatible with Ultra Instinct and Ultra Ego, meaning that Vegito/Gogeta will never make an appearance again.
Vegeta first attains Ultra Ego against Granolah after his Super Saiyan God SS Evolved is overwhelmed by the Cerealian. The transformation was powerful enough to cause Granolah to stumble back in noticeable fright.
Gohan Beast is Gohan's most powerful new form. Unlike the more straightforward Super Saiyan God forms, this one is based on Gohan's more animalistic transformations that he had as a child.
While Dragon Ball's Goku has unlocked god-like powers of his own, he still doesn't stand a chance against Lord Beerus, the God of Destruction if the two were to ever fight again. There is, however, one classic Dragon Ball hero who actually could fend off Beerus with one ingenious attack.
Goku achieves the ability to use Ultra Instinct Sign at will during his training with Merus, a trainee Angel who also possesses the Ultra Instinct ability.
Goku's battle against Gas just unlocked his ultimate form - a reimagined version of Ultra Instinct that allows him to fully tap his emotions. Warning: contains spoilers for Dragon Ball Super chapter 85!
Super Saiyan 3 Goku at full power has a battle power of 24,000,000,000, 2 billion above Kid Buu's level.
First off, there is no evidence which states UE is stronger than MUI, but they are kind of both based off of Instinct and a State of being from being in a specific mindset[Only flaw - loss of focus = form deactivation]…
Vegeta already has a far superior base form to Goku and the level of power displayed by both Ultra Ego and Ultra Instinct proves it.
The fusion between Ultra Instict Goku and Ultra Ego Vegeta makes Gogeta the most fearsome warrior in the multiverse. He would be able to dodge attacks and effectively counter at the same time, leaving no opening for Beerus.
Hakai is a technique that can only be achieved by a god of destruction. If you are not a god it is impossible to master the hakai technique. But that's only looking from the anime. In the manga Goku is able to learn hakai in a fight against fused zamasu.
The God killer! ULTRA Vegito's vow to kill all Gods. ULTRA Vegito is the main protagonist of the Dragon Ball Super UV series by CALLMEARJ. ULTRA Vegito is the resulting fusion between Perfected Ultra Instinct Goku and Ultra Ego Vegeta by the use of the Potara Earrings.