There is no "one game fits all". For me, practicing 14.1 builds confidence for pocketing balls, as well as tight cb control. If you play a lot of 8ball, practice straight pool for a couple of weeks and you'll find yourself running out little 8ball racks more often.
9 or 10 ball provides opportunity to let your stroke out, hitting 2 or 3 rail shape quite often, which helps develop speed control and a good feel for playing position off the cusions. But not the greatest games to learn tight cb control. I mean, as long as you have the angle to get to the next ball you're playing good enough position to run out. An inch off here or there isn't usually a run stopper. But "good enough" position isn't so hot when playing 8ball, straights, or one hole.
Near Pool is a great way to work on your creativity. If you've never played it, look it up. It's a great game for fun or gambling.
UPDATE: Can't find "near pool" rules anywhere. The way we played it years ago was simple: You can shoot any ball and score a point, but you must hit the nearest ball first (the ball closest to the cb). This ball can be pocketed straight into a hole, banked, kicked, used as the first ball in a combo, used for a carom into another ball, etc... We played no slop -- call all shots.