14.1
14.1 or Straight Pool is the King of the Pocket Billiard games. For many years it was the game to determine the World Champion. Due to Pocket Billiards politics of trying to promote itself into a spectacular media Sport, the game of 9-Ball became the popular choice for TV exposure, because it is quick and easy to understand by the non-poolplayer. Be assured though, that virtually every great player over the last 40-50 years had or has a very strong background in Straight Pool. This is, in my opinion, the primary reason the Europeans now dominate the Americans, because of how much Straight Pool they do play on a regular basis.
So, if you are looking to add a step to your game, taking up 14.1 is an excellent choice. Although, I would like to warn you, it is very intriguing and it may captivate your soul. If you can ever get to the point of being able to run 30 balls, you will be hooked for life.