I prefer CS:Source, it's got a 'cleaner' feel to it and is more addictive to play (for me anyway). I always come back to CSS, fast server connections, good weapons balance in teams, great classic maps whereas I have played ROOst about three times so far. I never come back to it, too much work to get into a decent server and takes way too long to load a map also no progress bar and the game doesn't feel as 'fluent' and the controls feel too clunky almost on ROOst. I feel CSS is a better playing experience alltogether, even though not as many features.