WCS has great flow. ramps are pretty easy to hit and feel good. the "goal" shot and callout are incredibly satisfying. gameplay is intuitive, but deep. best kind.
just last weekend, a staggering drunk non-pinhead at a bar asked me how to get multiball on the WCS i was playing there -- i explained it to him, and he proceeded to get multiball on his next game (he drained all three balls almost immediately though).
multiball is pretty easy to get, but not automatic. you've gotta hit a series of about 5 shots to light the lock, then hit the left ramp to lock the ball, then hit a scoop to start multiball. the wizard mode is pretty hard to get to, it's more involved. but it's one of my favorite wizard modes. you have to outscore your opponent in the World Cup finals by scoring a bunch of goals in a certain amount of time. the game has a professional play by play guy who does a running commentary.
honorable mentions got to NGG and Champion Pub.