>>2796954
A few benefits:
>more legroom
>shoulder space
>space to do work on laptop (or gaming if you are so inclined)
>better food
>complimentary water
>access to lounge with shower, bed, food and drink at airport
>priority boarding / check in
>onboard comforts, including allocated climate controls
>etc.

Economy is "sit down and shut up" class.
Business is "are you comfortable?" class
First is "what can we do to make you happy?" class.