I like the original Dragon Ball series mostly because there was less screaming and it didn't take 30 episodes to get through 5 minutes.

I would say Z. It's the one that brought me into the franchise. I remember being in school and looking forward to coming home every day to see it on Toonami before they moved it to Saturday, then moved it again to Adult Swim. I feel like (so far anyway) Z has the most content to offer, and since it spans over such a huge amount of time, allowed for a huge amount of character development. My only criticism would be the battle on Namek between Goku and Frieza. "The planet will explode in 5 minutes." - 15 episodes and 5 hours of dialogue later - *BOOM*

I went with dragon ball.

While DBZ gets pretty close, I liked dragon ball just a little bit better because of the overall atmosphere, something that I felt dbz had a little bit less of.

But really, I look at dragon ball and z as the same series, because they were the same manga and because it are the same characters, etc.

To me, there was good and bad in all the series, however I enjoy them all, with the Super Saiyan God Super Saiyan Exception of Super, but I don't feel like ranting on in multiple paragraphs as I have before about it. Hopefully my super charged transformation of Exceptions, should help you guys understand my disapproval (But mostly Beerus). XD

As for the best, in my opinion... I give it to DBZ (non Kai, although I do love the opening song), with Dragonball a close second. DBZ was the first one I've seen where they were fighting enemies that were clearly stronger, like Raditz. They had to use strategy, teamwork, some special surprise skills, and lots of luck, and it was still close, even losing a main character. I had never seen that before in any other show at that time. I loved watching those fights.

I did like GT, it had some cool stuff going on, and I don't care if you despise GT, watching SSJ4 Vegeta and SSJ4 Goku fusion dance into SSJ4 Gogeta was still one of the most amazing scenes ever, I'm getting goose bumps as I'm typing this, remembering the scene. I had recorded that episode on a VHS tape, and played it until the VCR ate it (Stupid VCRs...).

I did like some things in Kai, but it did seem to jump around a lot, which would have probably confused me more, if I hadn't watched the original DBZ. And some of the changes in dialogue disappointed me. So... There's my opinion.

In summation, DBZ.

The original Dragon Ball will always be my favorite. I loved Z and GT wasn't as bad as people say it was, but nothing will ever compare to the original when Goku was just a kid. There wasn't any "I can't beat this guy... *transform*" or super long filler (though DBZ filler was good, I'll give it that), and the story was just amazing.

Dragon ball Z is easily my favorite, mainly because of the story and the fact that it has all of the stuff beyond the Cell Saga as well. Dragon Ball Z Kai just sort of dropped off after the Cell saga, which sucked. I loved all the transformations and filler that everyone else seemed to hate, too.

I didn't like the Dragon ball anime at all, but the manga was pretty great, and it was pretty quick-paced as well, which made it a quick read. 

As for Dragon Ball GT, it was horrible. The only thing I can put up with in it is SSJ4 Goku and Vegeta vs Ultimate Shenron, the rest is garbage, and even in that fight, Vegeta is astronomically weaker than Goku because they broke Vegeta's character completely and utterly. I loved Vegeta, and they broke him. And then they tried to incorporate the fams and some drama and all of that, but they failed miserably and it came across as very, very cheesy.

Dragon Ball Super, while it has its faults, including animation that isn't as good, successfully incorporates things other than training and fighting into the series, and I really liked that, as well as a completely new level of power for Goku and Vegeta. I like that they're still climbing the ladder that no one's ever been able to reach, and they're nowhere near finished yet.