I prefer manga, mostly because I'm the slowest tv watcher in the history of ever. I'll watch one episode a day for a few days...and then a few months later pick up where I left off (not because the anime isn't good or anything, just how I am). But a manga I'll read 5 in a day.
I think it all depends on what you prefer. I like reading and seeing the art in front of me. A friend of mine prefers watching it and hearing it. I think as long as the vrersion you are watching is good (for example, I'd recommend reading Fruits Basket over the anime, but for Ouran High School Host Club, the anime version sticks well to the story, so if you like anime more than manga, go for it!)