Having given this way too much thought, I think the problem with the Wizard is that their strength is very situational. They have a tool for just about every conceivable situation, but they can't have them all at once. The right spell selection at the right time can invert the difficulty of encounters, or overcome challenges in ways the DM hadn't expected, and it's these moments that most people who feel the Wizard is too strong are really complaining about.
Because the opposite can be true as well; there's a fairly low floor for the class, where it sits at the bottom of the hit point pool, lacking armor, and having to spend vital spell slots on defense. Times when enemies make saves or are immune/resistant to damage and status effects, or where there's no optimal place to drop an area spell without harming allies.
Even the mightiest of spells, which can wreck a large percentage of enemies, can be foiled by an enemy spellcaster with dispel magic or counterspell, foes that can teleport, etc..
There's a reason "Schrodinger's Wizard" became a meme after all. So when the Wizard is firing on all cylinders, they can seem unstoppable, able to outperform almost every other class. But their ability to do that is very dependent on factors that cannot be predicted.
How open is the DM to shenanigans? What are their rulings on edge cases like? What is the party makeup? What enemies are common to the campaign? How much advance knowledge about a given situation does the Wizard have? Can they long rest before a big engagement? How many spells have they been able to put in their spellbook, which takes opportunity, time, and a decent gold investment?
How limited are they on valuable material components? What magic items do they have access to? Does the DM allow them to scribe scrolls? Are scrolls often found as treasure? How rigorously do they rule on things like getting the scroll to hand, opening it and reading it? Do they even allow reaction or bonus action scrolls?
What house rules are in play? What spells are allowed? PHB only? All WotC products? 3rd party? Are there bans to consider?
Then you have player skill; a Wizard who thinks fireball is the be all and end all of magic and spams firebolt and shield when not casting it can be a menace, but is likely far easier to deal with than the armchair tactician who focuses entirely on destroying the enemy's ability to act.
The ceiling for the Wizard's performance is unbelievably high, but whether or not they can be consistent is completely up in the air.
The main issues with the Sorcerer, I realize, are that they are more extreme than the Wizard; with their lower versatility they can seem crippled at times, but when their spells are the right ones for the job, the addition of Sorcery points to augment them can theoretically let them go beyond even the Wizard- but the opportunities are far less likely.
Because of these variables, rating the Wizard is impossible. It's like the DM who gripes about the Monk because powerful enemies keep failing saves against Stunning Strike; you can mathematically prove that the Monk isn't as good as all that, but they will go back to that time when the Monk made all the saves, ran around the battlefield with impunity, were immune to missile fire, dodged all attacks, and completely demolished the BBEG!
Personally, I think it's high time WotC sat down with the spell list and realized that a lot of their balancing is still based on legacy decisions from as long as 50 years ago. Do they need 9 levels of spells? Are Fireball and Fly really 5th level abilities?
Maybe it's time to cut down on versatility, or pare away the destructive powers of the Wizard and give them exclusively to the Sorcerer.
There's a lot of ways the Wizard can be rebuilt and rebalanced, but the problem is doing that requires change. Lots of change. And for people who feel that the sacred cows of the spell list are part and parcel of what makes D&D, well, Dungeons & Dragons, that might be a bridge too far, which is always something that Wizards of the Coast will have to consider.