There are tons of very effective metrics used. Passing %, passing amount, chances created, second assists, conversion %, shots on target %, save %, tackle win %, minute per loss of possession, minute per error, etc.
Which sites for stats do you prefer?
I like them too and agree that a lot of the ones you mention are interesting. My one complaint with a lot of stats is simply that they could be so much more sophisticated.
Stats like 2nd assists, chances created, successful through balls accentuate the effect of the type players I've always loved to watch. Actual finishes are seldom as impressive as those slightly-grazed back heals that start the dominoes' fall.
With others like chance conversion percentage, for example, I tend to think they often tell us more about the type chances a certain striker is getting than his quality. I suppose it's good remedy for the misconception that the strikers for your team always miss more chances than others.