Imagination.
Ok here is why i prefer bleach over naruto.
Tite Kubo has imagination.
Unlike naruto's author, Tite Kubo released other manga before Bleach, and they were all really good.
The problem with naruto is that it lacks imagination. I can tell pretty much 90% of the time whats going to happen, what it will look like, and what will everyone say.
While bleach has a smaller story arc, the imagination in character design is a lot better.
well naruto in the beginning looks more like it was sketched at first hand not that im much of a manga reader but yeah this my thinking... while bleach, yeah it has simple lines but their used so well it looks better. the only place naruto-series ever looked similair towards the manga of bleach is on the psp-games with the static images... they are drawn in the same way ;D