DB was the best when it was called Dragon Ball, meaning before "Z", it had adventure, challenge, martial arts, comedy, and it was less predictable.
Dragon Ball Z was fun to the end of Frieza Saga (Even Akira Toriyama planned to end DBZ when Namek exploded, and Goku went missing in space)
The only exciting thing of Cell Saga, was Gohan's SSJ2 transformation, the only thing that I liked about Buu Saga was the very beginning when Majin Buu lived with Hercule, and when he went evil.
Most movies are bad too. GT was nearly complete shit, but it had a good ending.
In DBZ, it's pretty evident that Akira Toriyama starts getting ideas from Superman.(DBZ was never planned, so Goku, and King Piccolo/Piccolo were never considered aliens). Goku came from a doomed planet was one of the few remaining, he is approached by other survivors seeking to rule the planet Goku grew up in (What is this, General Zod again?). Goku's father was an important figure in Planet Vegeta, sent his kid to Earth, and predicted the doom of Vegeta (Wow really? Jor-El is one of the most important scientists of Krypton, predicted the doom of Krypton, and sent his kid to Earth). By the beginning of the Namek Saga, I was asking myself if it was the same series I was watching, because it went from monkey boy prodigy of Martial Arts that goes on adventures to save Earth and his planet, to Alien planet buster shoots a kamehameha and it's not even a big deal anymore, then the same plot formula started with "Oh no a new villains arrived, we got beaten, we trained, transformation, we take turns against the bad guy, and we win by just fighting, no clever plan involved". The title it self lost it's meaning, Dragon Balls were so easy to find now, they can fly, and find the Dragon Balls in seconds "Oh no Krillin died, good thing it's not as hard to revive him as the first time in Dragon Ball, we'll just gather the Dragon Balls in a matter of moments and yay Krillin lives again". The fights turned to complete patty-cake stuff, from the fights in the martial art tournament in the second season full of cool, diverse fighters and moves to everyone blasting the same energy attack with a different color scheme, and name, patty cake fights, and LOTS of screaming to grow more luscious blonde hair until it burns of your eyebrows (Looking at you SSJ3).
If there is gonna be another DB series, I'm hoping it involves new characters,martial arts, and actually about collection the Dragon Balls with effort. Not about some wanna-be Egyptian god wanting to fight Goku.