for skill it would be Pot Limit Hold 'em or Omaha. Many more tough calls to make as opposed to the new version of "push 'em in" No limit hold 'em. This issue was discussed in a Card Player magazine a few months back.
Liars poker best game by far, I played every game mentioned, Liars poker most skillfull, casinos hate it becasue most popular form is mano e mano and casino cant earn off of it.