WorldWinner power a large selection of online skill games with many thousands of players online at one time. A few years ago, WorldWinner bought another very popular skill game site, SkillJam and they have now shifted all of the SkillJam players across to the WorldWinner network as well. So, if you're looking for a place to play with the most skill gaming players around (mainly from the US),then that'd be a good place to start.
Skill gaming networks like WorldWinner do have fun online games (including the pool games by WorldWinner) but as they have so many different games, they do not always have the best version of a particular game.
Pure pool game networks where that is all they do (an usually they are download games) often have the best pool game software if you're looking for the most realistic game you can find.
However, if you're looking for a fun, entertaining game and part of what you want to do is play against as many people as possible, then the pool game by WorldWinner may be what you're looking for.
They have WorldWinner 8-ball Pool which is a standard version of the 8-ball game, they also have WorldWinner 9-ball.
If you're looking for these games on their site, they have them listed under "Sports Games". I can't quite say that I would consider 8-ball and 9-ball sports games but I guess they have to list it under some title and they have so many other games it's not too surprising that they need something to set these games apart from the puzzle style games that WorldWinner are most well known for.