I honestly can't say that one is any better than the other. (I love them both.)
Although they follow parallel lines, they two distinctly different shows, so for me it's hard to compare them. It's not a simple as say comparing Ouran High School to Soul Eater. They're just too different to be in the same category.
Now, when it comes down to it. They both have way too many fillers for my tastes, but while Bleach seems to have more... Naruto just seems to drag about getting Sasuke back. Seriously, why doesn't he let them drag him back and then just leave again?
But then again, SPOILER possibility...
Bleach doesn't seem to freakin' end. Really? They defeat Aizen and the story continues?! What? Did I miss something there?
In the absolute end, I pick Naruto as the better anime. Following both shows character developments, Naruto has made me actually ride the emotional roller coaster. Crying when they die, crying when they come back...
Naruto, with Bleach a very close 2nd.