Maybe my opinion's in the minority, but I guess I see various hi-fi forums as having various strengths...
Actually, I've NEVER visited the "forum" or discussion section of AudioGON, I just enjoy it for the classifieds and occasionally show reports.
I don't think ANY other website can top AudioGON for great selection of used gear, including EBAY.
(I miss the little audio classified magazine through the "snail mail" called AudioMart, which was a little gem, but evidently defunct now)
But I like AudioCircle for the fellowship with my hi-fi peers. Again, I don't think AudioCircle can be beat for that.
Bottom line, at least the way I use them, AudioGON and AudioCircle are apples and oranges. Both are good in the diet, but they're different.
Jerry