I think Manga is quite a bit different from anime. I was originally introduced to Anime before manga. But then since anime is typically based on Manga... and me being the impatient person that I end - I typically end up just reading the manga once I've finished the anime in the case of an ongoing anime.
I think examples of manga that I've read because of this reason is Naruto/Bleach/One Piece/HxH. Ouran High School Host Club and Vampire Knight as well. The thing is that I feel that Anime in general is a superior experience for the most part.
I think Anime is better because I don't have the mind to understand the action sequences properly when it's in manga. I feel that I simply skim manga for the plot content. In FMA, the battle **spoilers** between Al and the homologous and the exploding alchemist was soooooo epic. When I read the manga... I was like meh. Al is cool. But the anime... holy shit. I got nerd chills watching that battle. Al is such a badass in that scene.
So now you know why I prefer anime over manga almost all the time. The action and animation, along with the music makes the experience better I feel. That said, there have been many manga series that I've read without even bothering to watch the anime adaptations.
I'll be putting manga specific reviews into this section. One manga that I really wish was animated is tenjou tenge. I really enjoyed tenjou tenge even up to the point where shit got weird and didn't make sense. Same thing with History's Strongest Disciple: Kenichi. The **spoiler** fight between Hongo and Jeningzad. Shit, that is too amazing.
One thing funny about my manga reading is that with ongoing manga series I tend to forget where I am.. or if I've finished that series. I've actually read Vampire Knight twice. Because... I forgot that I read the ending. Same thing with Tenjou Tenge. I remember exactly where the anime ended despite not watching it for awhile... but I definitely read the manga at least twice before I remembered that I actually read the entire series.
tl;dr - anime is better than manga for me. but I can't resist manga because of story reasons.