This saga isn't really my favorite, but I would have to say it's close. The Red Ribbon Arc (Red Ribbon Army Saga, General Blue Saga, Commander Red Saga) are amazing to me. Not because of the villains or the fights, but because of the character development. In this saga, Goku becomes a real hero, he witnesses death first hand which is a life changing experience for him. He also starts on his long streak of growing stronger and stronger with each saga by training with Korin. Overall I think this is where Dragon Ball really picks up.
I think its close between Cell and Buu saga, but ill have to give it to the Cell saga. Vegeta goes super saiyan for the first time, Future Trunks is introduced, Gohan stops bein a bitch and does somthin cool for once, and vegeta uses an epic final flash...
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