いちばん details

Examples

the most … in a set — superlative over three or more members

どの季節きせつがいちばん好すき？

dono kisetsu ga ichiban suki?

Which season do you like best? casual

日本にほんでいちばん高たかい山やまは富士山ふじさんです。

nihon de ichiban takai yama wa fujisan desu.

The highest mountain in Japan is Mt. Fuji. neutral

家族かぞくの中なかで母ははがいちばん早はやく起おきます。

kazoku no naka de haha ga ichiban hayaku okimasu.

In my family, my mother gets up the earliest. neutral

Formal prose swaps in 最も (世界で最も高い山) — いちばん in a written report reads chatty, which is why this entry has no formal example.

より
より ranks two named items against each other; いちばん ranks one member above its whole set (クラスの中で) — with only two members the superlative gives way back to より/のほうが.
のほうが
Same question-and-answer frame split by set size — a two-item どちら question is answered with のほうが, a set of three or more takes いちばん; 二人の中でいちばん is prescriptively wrong, and のほうが can never rank a whole set.