I am cool with shoujo-ai and shonen-ai.....but yaoi and yuri just goes a bit to far, I don't like it when they get all touchy and stuff.......Like Battle Angel Alita fan 1989 said, "They just weird me out."
But the worst manga ever is Luftwaffe 1946......believe me, crappy art and story and everything is totally confusing. And I bet none of you ever heard of it.....and you better keep it that way.
And the best manga I read is Berserk. It written somewhere here what I think of it http://www.theanimegallery.com/forums/topic/267
"Vae Victis" - Brennus, after explaining to the Romans that they better pay up, fixed weights or not, or else...