Ah, I voted before reading the complete post.
I prefer anime more, because sometimes I just enjoy anime series more, but I do think when I do get to read the manga, the manga is always better.
So it's split. I prefer anime, but I think manga ends up being better - weird, huh?
The person above me also makes a valid point. I absolutely hate reading a manga while it's still being released. Most manga is set up on a cliffhanger at the end so you'll want to buy the next manga. It grinds my nerves when I'm really into a manga and have to wait for the next issue.
At least with anime if it's ongoing and the ending it's pretty intense, I only have to wait a week before another one comes out - and a day of translating/subbing.
Translating and editing a manga can take a while =\