Tenchi Muyo!:
My personal favorite of the Kagatos. This is the first "boss" Tenchi and the gang had to face. He is looking for the sword Tenchi and for Yosho. He mainly hunted for these things for the light hawk wings. Kagato controls the ship Soja. This Kagato had control of Ryoko, making her fight Yosho 700 years ago.
I think this Kagato has more sophistication than the other. You can tell in the accent. This Kagato also has more powers than the one in Tenchi Universe. Just a fun fact, Washu was traped in Soja. Mihoshi accidentally released her.
Tenchi Universe:
This Kagato is the last enemy Tenchi has to face. An old rival of Yosho's, they trained together on Jurai. While Yosho later made his way to Earth, becoming Katsuhito, Kagato decided to use evil power to enhance his fighting skills. Kagato overthrew the Emperor of Jurai when Ayeka went to look for Yosho. When Kagato became Emperor of Jurai, his first order was to kill any family to the past Emperor, including Ayeka, Yosho, and Tenchi.
I don't know why, but after one Kagato, I had enough. Maybe if he had a different name. Remember, this is my opinion. I just thought he wasn't near as strong as his Tenchi Muyo! counterpart, although he did last until the end of the series, unlike the other Kagato. He also had some cool Jurai Knights with him.