I'll go against the grain a put a good word in for skyline (the long version). It's a good ride if you want to test your endurance a bit and don't mind climbing (2000m elevation compared to 900m on W2). Yes there's a fair bit of fire road in there, but then what about that bast@rd fire road climb on the wall!? ...that seems to go on forever!
Having said that though, if you want the most single track, ride Whites, July (shortcut skyline) and Penhydd. Do W2 only if you can be arsed with a neverending fireroad in the middle!