I've watched all of them (Except Onegai Teacher. I'll give you a tip.
Watch Amaenaideyo if you want a lot of Fanservice and Nosebleeding Comedy.
Watch Green Green if you want 'perverted' humor, like a bear 'doing it' with a fat boy, and 3 boys *Beeps* in the Gym room. (After all, this is based on a Hentai game)
And at last, Watch School Rumble if you want Romance Comedy.
Is it easier to choose now?
__________________
------------------------------------------------------------------------
I'm one of those who like the Anime shows better than the Manga! And don't complain about it!