I think just about all forums have declined in activity, by.... rough estimate, maybe 70% since 5+ years ago
My guess for most active adult forums....
1. gfy
2. blackhatadult
.. then a bunch mostly dormant forums... then..
3. asianwebbies, iq69 & legwebmasters
then all the rest, maybe 1 post per week, greenguysboard, mediumpimpin, foogie, tranny-masters, sponsorchat, digital point
adult forum
some that have completely turned off, closed down are now BeerAndBollocks, AskDamageX, JustBlowMe (now spammy picture forum)
Anyone know others that are still alive and kicking?