You forgot Boomer Shooter. I seem to get all my questions answered here. If I want to go read old posts ill go to AR15.com. I'm on M4 Carbine some too but mainly for the competition forums.
I guess I left BS out because I was thinking just specialty website for AR only - wanting to see which has the more knowledge on it. And no voting against something just cuz that banned you once before (WORMY) lol
AR15.com = Armchair commandos, Mall ninjas, Magpul worshippers, Newbies, and people from M4Carbine.net who troll there.
M4Carbine.net = DI Purists who will tell you that DI AR's are are not only more accurate than AK's, but are more reliable, can butter your toast, get you a girlfriend, AND inhaling the hot gases exiting the barrel has the side effects of Viagra... as long as you keep it lubed, of course. Oh and have correct buffer tubes and properly staked castle nuts and gas keys and use mil-spec parts and blah blah.... Everyone should carry a 1 liter bottle of lube around their neck and squirt their bolt down with lube after every magazine change like it's a wet t-shirt contest at night trips and you're controlling the hose... If you run a piston AR, you should die in a fire.
ar15armory.com = People who can't stand the poor forum design and ads on ar15.com and the mall ninjas that lurk there. Didn't build a colt up from scratch from surplus parts and/or run a piston AR system so not cool enough for m4carbine.net. They are forced to deal with an almost equally bad forum design at ar15armory.com. However, people who originally started at ar15armory.com will leave once they discover ar15.com / m4carbine.net.
Other = what I voted Go to each of the forums and take all info learned there with a grain of salt and make your own decisions.