Best Engine

1.Houdini 1.5a

2.Rybka 4

3.Stockfish 2.0

4.Fritz 12

do u agree?

Stockfish is defeats Rybka on my computer.

For these type of questions you're likely to get more accurate info by using a search engine, which is what I did

Your original statement is meaningless without knowing anything about your PC, CPU, amt of RAM and parameters (TL, ply depth of search etc) each engine is set one. Needless to say, most if not all of your answers here will be equally meaningless. Or are you quoting someone else's results?

You need to have each engine play the other engines several dozen games apiece using the same controls for every game to at least determine which engines are best on your own PC. For instance, Houdini 1.5 uses both my co-processors but Fritz 12 only uses one when analyzing.

http://en.wikipedia.org/wiki/Chess_engine

http://www.chesscreator.com/chess-engine-elo-ratings-houdini-leads-rybka-stockfish-and-critter

At the moment, as far as I know, 1.Houdini 2.Fire 3.Rybka4 4.Stockfish

Missing Fire, but still:

http://computerchess.org.uk/ccrl/4040/