Crysis is Far better , if you want to experience the new era of gaming ....
Team Fortress 2 FTW, playing it on Steam almost everyday
Portal is the best, even though there's no multiplayer.
You don't get much better computer games than the ones Valve produces. Out of the two you posted I would say Portal is the best one and the best game overall. Although I'm not a big computer gamer I have played portal and it is truly amazing.
I'd say Counter-Strike, just because I played it years ago back in the late 90's and it's nice to see how far this game as come from then. And I mean it made Valve what it is today. So to me that's the best computer game In my opinion.
For me, I like Call of duty 1/2. They're really nice for such an old game, + I like the story.
Starcraft 1/2, mostly because, they are well put together games, the multiplayer for it is also great. It's just a awesome game in my opinion.
It is very tough to give vote about all this game because i like all this game which you shared. Well from all of this game my most favourite game is Team Fortress 2. It is awesome game which i have ever played.
You can totally mod the crap out of CoD. But I guess you can do that for any computer game.
RUNESCAPE all the way, it's amazing and really addcting