Of course the manga is the go-to winner.
As someone who
ever so slightly prefers animation to manga: I'd probably have to say I'd like the Dragon Ball Z portion the best; mainly because I like the characters much more in Z, there's more universe-building, and I also feel Toriyama was at his peak in terms of character design and fight choreography during the "Z" era. I'm overall more entertained by DBZ; I can sit and watch a few episodes or a movie and it's heaven to me.
The
only reason I don't rank Dragon Ball higher than DBZ is because the Red Ribbon Arc drags horribly and uninterestingly in the both the anime and manga versions. The only saving graces in that arc are Taopaipai and Murasaki, which are highlights in what I would call the weakest story in the whole manga. Other than that, Dragon Ball is much more consistant in terms of quality than DBZ. I will say that the King Piccolo and 23rd Budokai arcs were excellent, and led into DBZ perfectly, with Toriyama's ever-evolving art, storytelling, and the stakes continued to be raised in each fight/story arc.
Dragon Ball GT has it's moments of course, but can't hold a candle to the previous material.
My personal ranking: Original Manga>DBZ>DB>DBGT
Nothing matters (in a cosmic sense.) Have a good time.