I am going to be completely candid:
I was a huge DBZ fan beginning in 1997. That is when it first showed on WPIX11 here in NY. About a year later, it started showing on CN and I remained hooked.
I mean, I truly was obsessed with DBZ. I loved it beyond words.
I watched this shit daily hoping for new episodes. I would get CRESTFALLEN when a new ep wasn't shown.
But now that I look back on DBZ and I compare it to DB, I realize:
DBZ was a crock of shit.
It was repetitive, stocked to the gills with filler (Fake Namek, 'Gone Fishin'!' eps...), and Cell and Buu were basically copies of eachother and, only slightly more obliquely, of Freeza.
Contrariwise, Dragon Ball was/is a fantastic anime. It is a magnificent mix of martial arts action, light hearted and pervy (in a non-obscene way) humour, fantasy, and adventure. There is very, very little filler, the characters brim with life and grow as the series progress, and the story moves from plot to plot without the sort of "here's ten episodes of Goku powering up!", or "here's how they get to ANOTHER Super Sayian level!".
Oh, that's another thing: DBZ ruined the fantasy elements for crap Scifi elements. They turned the Monkey King Goku into a fucking alien, one of many, and took them to dumb alien worlds. The characters also became ludicrously powerful and it became just about throwing ki shots at eachother, rather than cool martial arts moves like in DB.
I -highly- recommend DB, but I suggest skipping DBZ if you are an adult. If you are a young teen, it's still worth watching, but watch Kai - it is the abridged version that cuts out the crap filler and is remastered.