I agree with all you have said before about mainstream anime. But there are some exception. For example look at D.Gray-Man. It has lots of episodes, but it's awesome (of course, the manga is way better) and it's not as famous as Bleach/Naruto/One Piece so I don't know if it counts. Look at Bleach now, the manga is long, very long (50+ volumes right now) but it's good. The anime instead is awful. Just look at Ichigo, he is horrible in anime version. Naruto, if only was shorter, would be acceptable. One Piece, the longer one, has no chances. The style is for kids, the story is just an excuse to add tons of useless arcs. And the manga is also horrible. The page layout is awful, with tons of dialogues near each other. Very, very confusionary style.
By the way, a long story is not synonymous of an incoming disaster. Look at Berserk. The manga has 70+ volumes but it's very good.
Anyway, personally the only shounen anime with lots of episodes that I really like is D.Gray-Man (103 episodes)... I love it.