My favorite... Katsudon, Umeboshi, Dango and Tamagoyaki are all up there together, though i usually have curry with my tonkatsu because it tastes really gooood.
My least favorite would have to be Oden. With all that crap in there, there's no telling what someone else put in that. Plus, the broth and stock is usually disgusting with the noodles and the softboiled egg (which i always end up getting. XP)