You know what's silly is how Batmansince1939 did not ask for which point in time each series' characters were suppose to be at. If we to compare the most current of each series (i.e. the Buu saga levels of the characters for DBZ, and the current 'Part II' levels of the Naruto characters) then it would surely be in the favor of the DBZ characters, but I don't believe we're talking about that, are we? We are talking of which has the better storytelling, correct?
I find, sometimes, that Kishimoto's cast is so large that he poorly manages it and while the same can be said for Toriyama, at least by the latter years of the eleven year saga of Dragonball, Toriyama had found his the characters he was determined to focus on, and left characters likes Tenshinhand, Kuririn, and Yamcha behind. Toriyama focused on Gohan, Goten, Trunks, Piccolo, Mr. Satan, Buu, Kaiô-Shin, and Gokū (although decreasingly), while Kishimoto seemingly tries to focus on two of his characters (Naruto and Sasuke) 98% of the time and the other two percent to all of the other characters. It just feels like poor management.