manga I don't particularly like

Tenchi Muyo (aka No Need for Tenchi)
indeed, no need at all!

Oh My Goddess! (Ah Megamisama!)

Marmalade Boy and anything by that author
I used to be a big fan, but it all got old after a while.

Fushigi Yuugi, Mysterious Ceres and anything by that author
Again, I used to be a big fan, but it all got old.

Fruits Basket
I should refer to it as Fruit Basket just to be annoying. Good characterizations up to a point, but not enough to be really good. I don't like authors who jerk the reader around. There needs to be some delicacy about it. Plus, I don't like the main character.

Hikaru no Go
For the same reason as Fruit Basket.

Prince of Tennis
Again, good characterizations up to a point, but it's pretty predictable. Entertaining, but predictable.

Shaman King
For the same reason as Fruit Basket.