I would think knights are better because they can go pretty much everywhere, and are very useful in the endgame when forking kings, but bishops control a whole diagonal and can block pawns from queening. Just saying.
Even though they are 3 points, which is better to have, knights or bishops?

That has been debated since ever. The generally accepted standing as of now is a solid "it depends on the position". As a rule of thumb knights are more valuable in a more closed position while bishops are in favour in open ones. This does not apply always. A white squared bishop + pawns won't do much harm if the oponent has most pawns on dark squares or is cramped in... So one has to find what figure can be of best use in the given situation.

It probably isn't possible to say which is best, because the best piece for the situation you are facing depends on the situation you are facing. What does the board look like? Which squares do you need to defend? What are your attack plans? We know the power of a Queen and knight working together, especially in the corner. But one can also cover an enormous amount of territory with a bishop and a Queen. The pair of bishops advantage is also a strong one. This is the reason why they are both rated as having a value of 3. One is a hammer, the other is a saw. Different tools for different jobs. It's up to the carpenter to select the right tool depending on the job at hand...
What is the better piece to have even though they are both worth 3 points? Bishop or Knight?