In terms of power or quality?
Power, no kidding DBZ>Naruto. We're talking characters who nuke planets vs a verse where the strongest would be potential moon level with hype. Of course, as others have said prior, DBZ isn't the strongest, Gurren Lagann has mechas that make DBZ look babyish but that's besides the point.
As for quality, that's all subjective but I do say Naruto has more in its favor than DBZ personally. The thing is that DBZ has hardcore action but no real depth to it, Naruto has a superior story as far as content goes and a much more developed cast. Granted, I can't say Naruto does a fantastic job with its side cast but even then in DBZ I can't say that many of the characters really "grew" at all aside from, say, becoming nicer or something blatantly Shounen like that. DBZ is fun, mindless entertainment, but not much more in my opinion. If anything I'd say it's all about original Dragon Ball, where there was the martial arts element, adventure to add variety, and utterly hilarious comedy moments.
But as far as Shounens go I'd say FMA all the way. There are very few things I can see wrong with this series.