That is a really hard one. (Skip to the last two parts if you don't want to read this.)
Mace Windu is definitely one of the most powerful Jedi of his time. There are some statements that imply he is even more powerful than Yoda. When Yoda fought Darth Sidious he lost. When Mace Windu fought Darth Sidious he won because he has the ability to tap into the dark side. I heard the argument that Palpatine was holding back, but there is no real evidence to suggest that. In fact there are some statements that imply that Mace Windu was stronger than Palpatine. Anakin talks about how Obi-Wan is as powerful as Mace Windu and as wise as Yoda. That would imply that Mace Windu is stronger than Yoda. The strongest thing we have ever seen Yoda do is easily push a mountain over. That would mean Mace Windu should also be strong enough to push a mountain over.
Anakin was also very strong, but in the prequels he wasn't quite as strong as Yoda and Mace Windu. By the time Anakin turned to the dark side it is stated that he was stronger than Mace Windu and Yoda. That is until he fought Obi-Wan. By the time he fought Obi-Wan he lost because he was conflicted. There are several statements that say a character cannot do as well with the Force if they are conflicted. There is also the fact that since Obi-Wan trained Anakin he is able to counter a lot of his moves.
Both Mace Windu and Anakin are very skilled with a lightsaber. Mace Windu was able to defeat Palpatine. Anakin was able to defeat Count Dooku. Anakin was also able to defeat Ahsoka who was stated to be a master duelist at the time.
It is true that when Anakin got his suit he was nerfed. He was not used to fighting in a suit like that. However, later he learns to master the suit and he even becomes more powerful. It's stated that he becomes more powerful than Anakin. This means that when he is Darth Vader he is probably at the same level of Yoda and Mace Windu. (More evidence to suggest this is when he was able to use the force to shield his tie-advance from the blast of proton torpedoes which are mountain level.) He did lose to Luke once, but at that time he was conflicted and not as powerful as he usually is. You may be wondering if he is as powerful as Yoda and Mace Windu then why is he not able to beat Palpatine. That is because Palpatine also got much stronger in the original trilogy. If Darth Vader fought at Palatine in the prequels then he would win.
There is evidence to suggest that Vader surpassed Yoda and Mace Windu. Mace Windu should be able to lift a mountain with the force, but Vader was able to perform a feat in the comics that would be continent level. In Jedi Fallen order he was able to stop the water in the sea from falling on to him. That feat was estimated to be City level. Also there is a Jedi named Loden who was powerful enough to lift a mountain with the force, but he could not easily stop Starship blaster fire. It's stated that it took him all of his power to stop the blast. However, Darth Vader was able to deflect the Starship blaster fire with ease.
So it's probably a close battle, but at the end of the day I would say Vader wins. Tbh since he's the Chosen One it would make sense for him to eventually become more powerful than Mace Windu.
