Overall, manga generally rules in my book(ha...ha...pun intended)...
Anyways...0_o"
-Manga generally has better art, at least in Pokemon and Sgt. Frog's case. Also, like Zenith said, you can read the episode in five minutes, instead of waiting for stuff to happen. Manga artists generally add better detail and a greater idea of size and porportion. For instance, Mine Yokozaki does a great job of making realistic head and eye size, compared to other artists. In the anime, the eyes are HUGE, and the heads are wider than the girl's waist.
-Sure, the anime is free, but also anime online can also leave you with chances of getting spam and viruses. Also, manga's can give you like...fifteen episodes, with only $10 out of your pocket(if your american and going to the right place), that means your only paying $0.66 for each chapter. Your not going to go broke....
-Another point, mainly for artists, is that it is a lot easier to free-hand images from a manga, rather than an anime. The images are not only stood still, but also have plain dark lines, giving you good inking tips, just by free-handing them.
-Also, is that generally it is easier for someone to grapple dramitic speech in the manga by reading it, rather than hearing it.
"I did this for you!" Sounds a lot better read, than said.
Don't believe me? Watch the Pokemon anime.
Yet ANOTHER piont is that manga is made into anime. Anime wouldn't exist without manga. You wouldn't exist without your parents hav-never mind.