I would say Highschool of the Death. Loads of Ecchi xD
Besides the million panty shots Highschool of the dead was awesome!!!
like dav7 said, Space Brothers is one of my personal faves... reminds me of the times when i was that young boy looking to the stars to dream.
Rosario and vampire's kinda ecchi.. Its a harem and supernatural and its comedy. I'd recommend watching it :3
Or maybe Kampfer that has action..