This is SW WildSpace's Top Five Battles from Season one of Star Wars: The Clone Wars.
1. General Grievous vs Kit Fisto
From Episode 10, Lair of General Grievous

The reason this battle is number one is pretty self-explanatory. Its got
General Grievous in a lightsaber duel against Jedi Master
Kit Fisto, who was arguably one of the coolest Jedi to have ever existed. Its just something about the way he smiles. The way the two warriors exchange blows is very reminiscent of the old Samurai film duels, where the combatants are locked in a struggle of life or death. This episode has an epicness that is just beyond description.
2. Ahsoka Tano and Luminara Unduli vs Asajj Ventress
From Episode 9,
Cloak of Darkness

This epic fight features Sith Acolyte Asajj Ventress against Ashoka Tano and Jedi Master Luminara Unduli. Its one of the first times, on screen, we actually see some strong female warriors in some real action, which I feel is very important for the young female audience of the Clone Wars. The episode also does a great job at exhibiting the different styles of Jedi. Here we see Master Luminara, who is a very technical and by-the-book Jedi fighting against Ventress, who wields great power, but has very little control. As Luminara says, she is "unrefined, amateurish." Hopefully, we will be able to see more fights like these in upcoming episodes. Imagine a Shaak Ti and Ashoka versus Aurra Sing episode!
3. The Battle of Ryloth, Seige of Lessu
From Episodes 21, Liberty on Ryloth
There is just one character that makes this battle so high on our scale of epicness. Mace Windu. After not seeing a lot of action from the Jedi Master in the movies, this battle more than makes up for it, especially the assault on the bridge of the capital city, Lessu. That particular scene has to be one of the most memorable of season one. The way that the sound of the scene was muffled to give the viewer a sense of how the Jedi master's mind is so calm and focused even in the heat of battle was masterfully executed. By episodes end, I was simply left wanting more. That is the mark of a good episode.
4. Anakin, Ahsoka, and Aayla Secura vs Lok Durd
From Episode 14, Defenders of Peace

As an episode directed by
Steward Lee, a self-proclaimed Hong Kong action film fan,
Defenders of Peace climaxes in an epic battle filled with incredible action sequences. Clone Wars executive producer,
Dave Filoni, said in a behind-the-scenes featurette that anything directed by Lee would feature the characters in dramatic poses and that "every character would do at least one cool move." The battle sequences with all the Jedi are some of the most intense and coolest looking lightsaber scenes seen all season. One of the other pluses to this episode is that this is the first time we actually see
Aayla Secura in action and she kicks droid butt.
5. R2-D2 vs R3-S6
From Episode 7,
Duel of the Droids

R2-D2 was designed as an Astromech Droid to repair spacecraft and act as a navigator. This episode shows that the most famous droid in history is so much more than a repair man and truly deserving of such a title. From that moment "Goldie" first attacks R2, we can see the fire ignite in the little droids eyes. He has a mission to destroy the traitor that almost killed his friends and more than succeeds. Its also quite cool to be able to see all the little components that are hidden with R2 in action, especially the buzzsaw. Even without a face, Goldie's expression once R2 cut the line that was keeping him from falling was priceless. More of a novelty fight than an actual battle, we all know who wins this one before it ends, but it's always entertaining to see R2 utilizing his resourcefulness and "combat" capabilities against a foe his own size.