>best
It's not a persistent one, but the dragon generals are pretty good, at least for a while. I wouldn't count "Meanwhile, on dragon /tg/..." as one, but those are also comfy as fuck.
>worst
Probably drawthread. I might just be looking at the wrong times, but it seems about 1 part OC, 20 parts talking about people who haven't shown up in the thread for a week, and 79 parts requests.
>most degenerate
Dragon threads, aka "100 posts of discussion, then vore happens." Not that I'm complaining...