Which is more useful: Knight or Bishop?

Which is more useful: Knight or Bishop?

A bishop

but a bishop can move in only 1 colour :/

@3

AlphaZero rates B = 3.33 P and N = 3.05 P. Table 6

'The weaker the player the more terrible the Knight is to him, but as a player increases in strength the value of the Bishop becomes more evident to him, and of course there is, or should be, a corresponding decrease in his estimation of the value of the Knight as compared to the bishop' - Capablanca

A knight standing on a dark square can only move to light squares.
So a light square bishop can dominate it.

The easiest way to appreciate is to study 3 basic checkmates.
KBB vs. K is easy. KBN vs. K is harder. KNN vs. KP is hardest.

DAMN

I play a lot of games where people take my knight even though I get their bishop, is this a good move or bad move. (also I'm 425 in rapid)

@6

"people take my knight even though I get their bishop"
++ This is generally bad. You should think of BxN as a sacrifice of the so called 'minor exchange'
Sometimes it is good to take your knight even though you get their rook.
Sometimes it is good to take your knight even though you get their queen.