Stockfish is stronger than Rybka
Yes but in the list there is stockfish 2.2, the last version is 2.3.1 that is n.2 engine in the world, so bad list
You must be very critical of ranking such as these. There are many variables here, and some web sites (chess2u for example) that hold tournaments with engine vs. engine, and computer vs. computer. They have found that some engines are faster than others and will win more often under short time allowances, say 5 seconds/move for example. Others are stronger the longer you give them to run. It is also necessary to have each engine use the same opening "book" and endgame tablebases, run at the same computer speed and number of cores, and have the same RAM hash table settings. In the end, it is largely irrelevant since they all perform better than we do. Their main use, as far as I am concerned, is to check post-game analysis for oversights, errors and consideration of variations not seen during a game; and to reference other IM and GM level games that may have arrived at a similar position to see how they were completed. It makes no difference to me if I have the latest and greatest engine, since any of them can kick my butt.