I watched the anime first and then picked up the manga afterwards. And I actually liked the manga a lot more (so far, of course), the art in the anime doesn't look as good, especially the faces of the girls and the fights seem a bit lacking. So, I only regret that I didn't pick up the manga much sooner
Btw, could you tell me which spelling they chose in the English version for the members of the organization (only 3 so far I think)? Thank you