I don't know about 360 players, though I believe they had the smallest playerbase of the 3 platforms...and I believe the size of the playerbase (as well as intensity - how hardcore it is) determines how quickly a community develops and spreads effective strategies. I've played on both PC and PS3 though.
PC vs PS3:
Joining random games, it was about the same. The majority of people you come across aren't very good on both platforms.
As for the highest level of play...my guess would be that if you somehow found out the top 25 players among PC and PS3 communities, PC would probably have 15 of them, and PS3 would probably have 10. I wouldn't be surprised if the top 5 was all PC players.
If you matched the top couple of PC players against the top couple of PS3 players, I would put my money on the PC players... but it would be a good matchup. I don't think it would be domination.
Don't underestimate the ability of hardcore players to master a game no matter what platform they are on. They've put thousands of hours into the game, tried a thousand styles of playing...and even if they weren't on PC, they had the ability to study all the streams and youtube videos available. And keep in mind that some communities capable of producing hardcore players are limited to certain platforms...like the Japanese RUSE community is mostly on PS3.