In short, he thought that the Jedi were becoming too subservient to the Republic and the Senate. That was on particular display in "Choices," when he and Master Windu were working as partners.
Dooku and Mace Windu were friends before Dooku left the Jedi Order. They both went to Raxus to retrieve Master Katri's body, but Dooku instead uncovers the truth of Katri's murder instead of just retrieving the body.
There is no clear answer as to who would win Mace Windu vs Count Dooku, as they are both incredibly powerful Jedi. However, if it came down to a battle between the two of them, it is likely that Mace Windu would come out on top. He is known for his impressive skills with a lightsaber and his mastery of the Force.
They have a grudge against each other because, well, let's face. Mace Windu was not pleased to see Anakin at the Jedi Council Chambers in The Phantom Menace. He disliked the idea of letting a young boy join the order. And from then on, he never exactly created a bond with Anakin Skywalker.
His best friend had been given a gift that could have allowed the Jedi to help countless people, but Yoda refused to act. As a Jedi, Dooku couldn't stand the thought that his best friend was suffering without a purpose, so he hated Yoda and the Jedi Order for that. In the end, though, Yoda was right.
Like many of the other Sith, Count Dooku was incredibly proficient with the Force, even being able to win a fight against Yoda. Despite this, though, he still wasn't the best fighter with a lightsaber, and his Force skills were not nearly as powerful as Darth Vader's.
Bottom line, Dooku never considered himself a Sith. And he wasn't; he was a man looking to change the galaxy in a way the Jedi were unwilling to try. And that is why he joined the Sith and became Darth Sidious' apprentice, Darth Tyrannus. When Dooku became Sidious's apprentice, he was already an elderly man.
The showdown on Coruscant was a confrontation that took place in the Supreme Chancellor's Suite of the Galactic Senate in 19 BBY. It began after Jedi Knight Anakin Skywalker informed Master Mace Windu that Supreme Chancellor Palpatine had revealed his identity as a Sith Lord to him.
Master Windu Was Afraid of General Grievous - But Only in Star Wars Legends. Master Windu was a legendary lightsaber duelist, but even he had someone that he really didn't want to fight. That was Legends' General Grievous. There are plenty of unending debates that happen around the Star Wars franchise.
You know, the reason Mace Windu told Anakin to wait in the Council Chambers is because when he got back from killing Darth Sidious, Mace Windu planned on granting Anakin the rank of master. Yep. It's sad but true.
The count bested both Jedi in their duel, using the power of the dark side and taking advantage of young Skywalker's impetuous nature. But before he could land a killing blow, Master Yoda entered the fray. Not even Dooku's Sith-enhanced powers were enough for him to defeat Yoda.
Before Dooku was a Sith, he was an esteemed Jedi Council member. As Windu's senior by 30 years, he saw Mace grow up and mature in the Jedi Order. That's why he referred to Windu as an “old friend” in this comic.
Mission to Mathas. Padawan Windu was trained in the ways of the Force by Jedi Master Cyslin Myr. Following his early trials as a youngling, Windu attained the status of Padawan by becoming Jedi Master Cyslin Myr's apprentice.
With a potential Jedi Code-defying love affair with another Jedi, Dooku is more of a foil to his Clone Wars-era enemies, Anakin Skywalker and Obi-Wan Kenobi, with Dooku's lover, Jedi Master Jocasta Nu, possibly retaining feelings for Dooku well after he joined the ranks of the Lost Twenty.
The second part of Star Wars: Tales of the Jedi episode 4 is set shortly after Qui-Gon Jinn's death at the hands of Darth Maul, and it reveals the moment Dooku became a Sith Lord.
In one of the canon comics Sidious outright implied that Maul was pretty much head and shoulders above Dooku when adressing the potential. While Dooku was a useful pawn for him, Maul in the other hand seems to be actually his first choice as a heir before Anakin was really part of the picture at least.
Windu eventually gets the better of Palpatine before deflecting his Force Lightning back against him, which appears to twist and melt Palpatine's face as his body begins to smoke, turning him into the grotesque embodiment of the Sith that acts as the final antagonist for both Star Wars: Episode VI - Return of the Jedi ...
He left the scheming and negotiations down to other Separatists leaders and focused on upping his kill count and taking Jedi lightsabers as trophies. He hated the Jedi so much that Grievous even learned to wield lightsabers as a non-Force user, which was incredibly dangerous and usually foolish.
In the final days of the Clone Wars, Windu turned to Kolar again, calling on him, Saesee Tiin and Kit Fisto to arrest Supreme Chancellor Palpatine. Confronted by the Jedi, Palpatine threw off his guise and revealed himself as Darth Sidious.
Amedda was one of the few beings in the galaxy who knew Palpatine's secrets, most notably his true identity as a Sith Lord.
Anakin regrets this decision, and Palpatine reasons with him saying that Dooku was too dangerous.
The relationship between Sith Apprentice Count Dooku and Jedi Knight/General Anakin Skywalker is one of the main enmity relationships seen in Star Wars: The Clone Wars. Anakin has a personal vendetta against Dooku because he had dismembered Anakin's limb and cuased him to get a mechanical arm.
In legends, Dooku actually explains why he hates Anakin: He could feel Yoda's touch still lingering on the edges like a distant echo. Vividly his mind went back to their last meeting, on Geonosis: swords drawn at last, and finally equal.