Whirlwind & Mousin' Around get my vote for best. Mousin' has a few threads here regarding how much it has surprised people -- IMO it's one of the best "flow" games of Sys11 if you like keeping the ball moving. The ball whips around some of those loops damn fast. If I had to choose between that or Whirlwind.. it'd be a tough call
Worst.. I dunno, some people might say Road Kings. Jokerz didn't really do much for me and I found the sounds pretty annoying. I actually liked Road Kings more than Jokerz. I haven't played all the Sys11's so it'll be interesting to see what people say here.