If anyone is interested, DBZ Kai will be airing on Toonami at the beginning of this fall. A lot of people hate on Kai because of the change of English voice actresses, but Kai is really good. LBSH, the voice actresses have to get old sometime or another. It's the same way that I feel about some of Sailor Moon's new English voice actresses (RIP to the original Zoisite). They have lives to live just like we do. It's really hard to keep that in mind since we're all die hard fans of these storied franchises. Don't bother bringing up how much shorter it is taking out a few episodes & some flashbacks from some. The purpose of Kai is the same reasons for Sailor Moon Crystal.
It's a reboot of the original anime with fights being at a faster pace, & the personalities are cannon being closer to the manga. It also corrects a few mistakes/boo boos seen in the original one (as all other dubs). If I were a new guy to the action-packed cartoons, I would recommend the newer ones only because it's what's being shown right now & they stick closer to the manga. That's my only reason if they don't want to go & look deep into franchise as a whole, but I would do it anyway so I highly recommend it as a guy who was born in the transitional period. I was blessed to have gotten to watch these series as a kid so that I can live to tell about them. I get to point them out to newcomers. Not to mention that I'll have all of the CD collections of the series here soon with a few other franchises (Mobile Suit Gundam, Inuyasha, Yu Yu Hakusho etc)
However, like Sailor Moon, the original anime is a classical piece of work imo. I often watch both original animes while watching the newer ones. It's fun telling the differences between them. I do like Bruce Faulconer's music production. Nothing beats it, but Kai's fight music good also. Goku vs Frieza was the best piece of work from Kai. It's really fun getting to see all versions of them.
Another thing is I heard a few rumors of the series being redone again, this time with Gohan being the "actual" main protagonist taking Goku's place after the Cell games as Toriyama originally planned. Just a rumor though so IDK how true that is.
Sorry for the long post. Just wanted to explain a little bit about the series & some key differences.