Obviously I'm bias, but it has to be Georgia, right? The fact that there was a time last year when many posters switched to S-GA avatars because two of our deleGAtion was banned certainly says something, no? And while not everyone is big on Atlasia, the fact that the two main contenders for the most recent Presidential election are from Georgia says something too, correct? The evidence is undeniable.
Britain isn't a state, so I'm not sure if it counts. Although if we are going countries, Poland should get a mention; I can only think of two Poles on the forum, and both are endlessly entertaining.
Washington, Pennsylvania (Angus is from PA, right?), North Carolina, and Massachusetts are good ones I'd like to echo. California has some good posters, but the fact that it's the size of several normal states gives it an unfair advantage.