Caran D'ache is a Swiss pencil brands, and it is very popular among both amateur and professional artists. Their watercolour pencils, Caran D'ache Supracolor, are one of the best you can get. They give a lot of colour and a soon as you add water to it the colours come to life.I recently borrowed my sister's set of these great pencils so I could test them myself.
Although I prefer watercolour paint instead of pencils, I found these pencils extremely rich in colour.
Caran D'ache Supracolor pencils are expensive, but they last a lifetime.
Fortunately you can buy them in smaller and larger amounts. You don't need all 120 colours because you can mix colours.