- Music: Intro/Exit music are important for anime, and the themes change every season (sometimes even more often). I thought Bleach won out in terms of music, since it tended more towards Rock music (my taste) and Naruto to Pop and Country (not my taste). However, Naruto did have the intro song, "Hero's Come Back!!", which is really quite catchy, for the first season of the second part (Naruto Shippuden). I give Bleach the slight edge here.
- Side Characters: One of the strengths of both shows was the depth of interesting supporting characters. On one hand (Naruto): Jiraiya, Sasuke, Kakashe, on the other (Bleach): Urahara, Renji, Rukia. Goes way deeper on both sides. I'd have to call this a draw.
- Plot: Both anime had quite interesting plot arcs. Bleach, especially at the beginning, had a lot of false starts in terms of consistency and some characters that were brought on that never reappeared in a major way (i.e. Ganju). Naruto's creator had a clearer vision from the start for the consistency of his world and the characters in it. I give Naruto the slight edge here because of this difference.
- Filler: Both anime were so successful that they did not go on hiatus when they reached the end of what was available in the Manga series. Rather, they continued with "side" stories invented by the anime writers. These so-called filler episodes ranged from painfully bad to just bad for both series. However, the filler at the end of the first Naruto series was especially bad. If you watch these shows, look up what episodes are filler and just skip them (google "Naruto no filler" for example). I guess I shouldn't judge either series based on its filler.
- Endings: Bleach ended with a very poor plot arc. Naruto has just gone on and on with filler. I think they could still all be in a dream. I just can't be bothered to wait for the final episodes with the real ending. From movie spoilers I know Naruto ends up married to Hinata and she becomes a housewife. It's just sad all around. I call this category a draw.
- Main Characters: This is the aspect of the shows where I decide for Bleach. Naruto is portrayed as a bit of a buffoon. He is socially awkward and not good at academics or strategic thinking. In the series, it is other characters that have to say he is charismatic - and we are supposed to believe it, even when he clearly is not. He goes off "training" for long periods of time and other, more interesting characters dominate the series for weeks. It is a relief. On the other hand, Ichigo is a smart kid with honest social skills. Bleach is the clear winner here.
Basically because of this last category, I think Bleach was the better show. I do have to say that I (mostly) enjoyed them both. Remember to skip the filler!