For some months now I've been reading through a bunch of Cthulhu mythos stories, and the setting is really cool. Naturally being a tabletop gamer I couldn't stop there and had to look if any games were written for it, and sure enough google quickly points me to Chaosium 's 6th edition rules. So I grab a copy and start reading.

Then I went back to google to find out more about the game and get some strange results. A D20 version, Trail of Cthulhu, what? These aren't different editions, but are entirely different games using the same setting?

Not wanting to spend $90 on rulebooks since its seems highly unlikely that I'd be able to actively play that many different game systems, I'm kind of stuck on which direction to go.

From what little I've been able to figure out it seems like the mechanics of the D20 game are almost exactly what is used by D&D 3, which makes learning it much simpler. The Chaosium rules are fairly simple, and impose few mechanical restrictions that would hinder character creation and development thus making role play very important. For example none of the skills are dependent on character attributes, so your high intelligence low strength can still be competent in a fight because his combat skills are high. I have not read any of the Trail of Cthulhu stuff yet, so I've no idea what its angle is.

I'm not really concerned about source books for settings or modules. It seems to me that since they all use the same setting adapting material from one to another shouldn't be too difficult.

I'm just curious how the mechanics are different between them. Personally speaking; I prefer games that are full of role play as opposed to lengthy dungeon crawls. Though the folks I tend to game with seem more interested in interesting combats that are linked by a larger story.

Has anyone played all three? Can you offer any insight to the mechanics in each and what sort of game they work best for?