I believe it really depends on the series. Many series need to be only one kind of media to express their story at best. In my opinion:
CLANNAD,
Byousoku 5 Centimeters,
Ano Hi Mita Hana no Namae o Bokutachi wa Mada Shiranai etc are much greater than their manga's. On the other hand,
Sakamichi no Apollon,
Bakuman,
Black Cat etc manga are better than their anime's (although for the first one, the difference is not that much).
A lot of anime's these days emphasise too much on Fan Service scenes, understandably because they want to make money and there are people who just want those scenes; manga's have those properties, too, but the proportion of manga's with a lot of pointless Fan Services and bad storyline to those without is far less than that of anime.
Anime's can do what manga's can't, and vice-versa. After a while, you will know what you can expect from an anime from looking at screenshots and characters, and will be able to decide if it is worth watching or not.
Quote from RandomUser
I prefer the manga version because I can get through a series faster then watching the anime.
Usually true, but not always. Try watching JoJo anime's...
Last edited by Fantasier at 9:09 am, Oct 27________________
Don't cry because your favourite manga ends; you would cry much harder if it didn't end at its appropriate length.