To me Nepean is the favourite, I admit I don't get around to the other tracks these days although the weekend at Griffith was great. Nepean just seems to get better every year, thanks to the people who put so much effort into it.
Going back in history I have fond memories of Moorebank scramble track,Vineyards short circuit, Boxers Creek, Neminga and Taree.
I also rode at SaltyCreek, Heddon Greta, and once at a grass track/scramble at a track near Longford in Tas. Does that mean I rode overseas???
But Nepean is my favourite. cheers pancho. ps, I never rode at Bossley Bush but I watched once or twice, also watched at Henry Lawson Drive in the days when my bike was the treadly kind.