I had heard about the series while at school, but technically speaking my cousin was the one who introduced me to Dragon Ball; I remember right after school we used to stay at a day-care within the premises, and since we stayed there for at least 3 hours, he used to bring movies and stuff. One day he brought "Dragon Ball: Great Mystical Adventure", which was at the time the third and last movie of the original series, and all I know is right after that day I was hooked and didn't look back. Thanks to him I saw the majority of the original series, and then as time went on at school more of our friends also started to get Dragon Ball fever, so we eventually got to almost everything since we would lend each other VHS tapes with episodes, as well some of the movies recorded on them. Later on during high school I leaned about GT, which I saw thanks to another friend, who happend to also have the rest of the DBZ movies. Super I watched for the most part thanks to the magic of the Internet, but truthfully was underwhelmed until the last few episodes.
If I were to pick favorites:
Dragon Ball Z
Dragon Ball
Dragon Ball Super (it's okay)
Dragon Ball GT (meh)
Super Dragon Ball Heroes (whatever)
I still haven't watched Kai to this day, but I will in due time. I don't mind the filler episodes in DBZ, but given Kai was edited to closely follow the manga is quite an incentive. And as far as Abridged goes, I binged the series years ago, but haven't seen any of the newest episodes.