Anime that you doubted because of the cover art, but now are a huge fan of

[Star_Of_Hope]

That would be One piece.
Just because of the art I didn't pick it up for so long and now however it's the only ongoing anime that I follow.

 

[Blackangel]

probably yu yu hakusho and one piece for me
at first i hesitated but now i love one piece and the art is not completely bad now lol