Bishop or Knight?

I think overall bishops are much better than knights if you have 2 of them, you can oversee the whole board. But alas, every position is different, and you have to train yourself to evaluate minor piece value and pawn structure synchronization with the minor pieces

whatever you do...don't start favoring one over the other...if you base your play purely on say favoring your knights...even going as far as to moving them to prevent exchanging them that would be foolish. Various openings and the many variations in them will result in games where it varies because you can't always choose or prevent there exchange..Learn to work with whatever you have. I once played a game ...back when people actually played with real chess boards in" person"...with a guy who stated at the start of the game..."i love my knights" can't play without them...so...I pinned both his knights against his king and queen and took them both...messed his game up bad ...lol

this is an example of a bishop pair which I played yesterday which ilustrates quite well
how they combine each other
http://en.lichess.org/0GfXSZ2B#28
By move 14 I knew I was winning despite the material equality or having one pawn less, cause its very open
the position for the bishops, so the position it plays by itself.
I will post later some game, when the knight does some jumping between pawns and the closed position
Examples are always the best way to learn.

Having bishops or knights don't really give you an advantage in general. Bishop enables control of half a board, while knights enables controls of slightly over half a board, but moves slower. Anyway, in a game of chess the stronger side wins. Both bishops and knights are powerful if you can hold onto them in good positions.

Zugzwang69, you are right about what you say, but we are not discussing this, but instead we are considering wether a bishop or a knight is more usefull in X moment of the game.
Motion, nice mate, i wish i knew how to save games, after a blunder in my part, hours ago a guy mated me with the queen and bishops so fast i didn't even see it until it was too late.

Simen Agdestein (strong norwegian GM) said today that time has shown the knight pair is acctually very strong in open positions.

yes, as a matter of fact it is one of the best defenseive positions you can have.