Bishop or Knight is more valuable?

Hmmm oh yeah thanks!

its bishop most of the time

but sometimes knight ok?

no need war

No. 

Happy to help

This is true, but of course my version of Knights vs Bishops was simplified. There are other differences which I'm virtually certain someone of your chess rating also understands the nuances for. Some examples:

-Knights generally make better blockaders of passed pawns

-Bishops typically do better at blockading long pawn chains

-In endgames, Bishops are usually preferred when there are pawns on both flanks whereas Knights are usually preferred when there are pawns on only one part of the chess board (since Bishops can zoom across the board much quicker than Knights can travel) 

and so on

It depends on the position. In open positions, the bishop's diagonals are open and allow it to control far more squares than the maximum 8 squares a knight can control. But in closed positions where the bishop's diagonals are blocked by pawn chains, the knight's ability to jump over pieces is fer more useful, making it more valuable. I prefer Bishops, but it depends on both your style and the position.

Knight, bishops totally suck at making forks.

Ok, good point

Bishops can’t do smothered mates.

I guess knights are better. 

That’s your logic.

The value of a piece is dependent on the position it is in. For example, if you have a pawn on the 7th rank and your opponent has no way of stopping its promotion it has the same value as a queen. Except maybe if your opponent can mate you right now. Then its value is zero. See?

The values commonly ascribed to the pieces are sort of an average over a very large number of positions based on experience. In a given position the value of a piece can be much higher or much lower than this hypothetical average. There are positions that are favorable for a knight and there are positions that are favorable for a bishop. You will have to get a feel for what these positions are and then you will be able to make better decisions re their exchange in a given position based on your own experience.

There is a set of lessons on this topic here:

https://www.chess.com/lessons/make-the-most-of-your-pieces

Two Bishops is clear. Lots of complicated argument and theory here. As Knights eat pawns they become weaker. As Bishops eat pawns they become stronger. So the answer to the question is that it depends on how many pawns are on the board. If they are immobile then Knights are better and if they are mobile then Bishops are better. The big difference between the pieces is that a Knight can be replaced by the other Knight but not so with the Bishops. Bishops can fork, pin and skewer but Knights can only fork. Linnear and non-linnear (unblockable). I would avoid a Bishop and Knight v King endgame at all costs even though I know the theory.

Chess: DerekDHarvey vs predadan79 - 326504024 - Chess.com I managed to swindle a draw due to the 50 moves rule with BNKvK but I had to claim it as we do in OTB>

Has thou ever heard of bad bishops and bad knights? That determines when thee should make a trade.

bishop by far

What?