Off the top of my head... Gokujo, i laughed so hard when i read that manga. What about GTO? 81 Diver? Hammer Session? Enma Touhai Washizu? That one was pretty funny too. Usogui, although it doesnt have much romance.... but still very good plot and nice humour too. Magi is also very good, with good humour, some romance later on, and very good plot line. Kindaichi Shounen no Jikembo and Jigoku Sensei Nube, are both classics. I could probably find a few more if i did a bit of searching, but thats about it for what i would recommend based on your criterion.