SJDS
Winner: 6/10 (Natalie was solid, nothing special, but solid)
Entertainment: 7/10 (Keith carrying this 7 on his back along with a couple of moments from other people)
Cast: 6/10 (Keith, Jeremy, Jon were the only people really memorable for me)
Gamplay: 8/10 (Post-merge was awesome, pre-merge was bleh)

Australia (I also haven't seen it in a bit)
Winner: 6/10 (Tina is a more memorable winner than Nat, but I can't single out big moments or key moves for her)
Entertainment: 8/10 (This may just be an off memory, but I remember this group being great @ confessionals + a good amount of classic moments)
Cast: 10/10 (Colby, Tina, Jerry, Amber, Rodger, Elizabeth, Alicia, Kimmy, Jeff, Skupin. Maybe the best cast of new people ever. I even liked less popular people like Mad Dog and Nick)
Gameplay; 6/10 (Very tough to rate old school Survivor gameplay, it's so much different from what you think of when you think gameplay now. Colby taking Tina to the finals over Keith pretty much sums up what's different about the game, though we've seen people make the same mistake recently *cough*Woo*cough)

I have to go with Australia here. Its cast blows SJDS out of the water. Even though I wasn't watching then, this was the season that cemented Survivor into pop culture forever, these people were legit celebrities whether you were pre-merge or there in the last episode. SJDS is very underrated though, deserves more love, especially for the unpredictability post-Rocker's GF quitting.