I grew up on comic books, so picking one series that the 'best' is pretty hard. One I particularly loved was the Forgotten Realms comics released by DC back in the late 80's. Unfortunately the series didn't have a very long run but the story was fantastic. On a good note, IDW Publishing has started a new series set in the Forgotten Realms setting and it's penned by the world's creator Ed Greenwood.
I have never really liked comics, but for a while I did get into the Kingdom Hearts graphic novel series because I enjoyed playing the video games. I prefer the style of manga drawings to that of regular comics.