The best colours for kitchen walls depend on the atmosphere you want to create. 

If you want a sleek, minimalist modular kitchen colour combination, go for clean cuts, fewer shades, and advanced cohesiveness. For example, a pale blue and sandy brown or grey and white kitchen would be categorised as minimalistic.

If you want something with more colour, you could pick different kitchen colour schemes with a fixed palette to maintain cohesiveness, which is basically just a way of making sure that your kitchen paint colours look pretty and not haphazardly thrown together.