Often used with the word naka
. "Yasui no naka de nani ga ichiban kirai desu ka?
" means "Out of all vegetables, which vegetable do you dislike most?
", or literally "Inside vegetables, what is (your) number one dislike?"
Also, probably the most popular (the Number One!) beer in Japan is Kirin Ichiban. Being underage when I visited, I was unable to have a taste, but I would imagine, from what I know of the prominence of bars in the Japanese culture, that the beer is superb.