I've found that I've gotten some good amount of readership on eFiction, Adult fanfiction.net and Fiction Press.net. I would post it on Nifty, but I don't wanna wait 6 weeks to be told my story won't be posted. Even if I did post on Nifty, I wouldn't be happy that it would take some one weeks to find the story since they have to shift through the rest. I don't mind shifting through, but not when I want a good story right then. It's just to much hassle to go through. I deal with it enough with my site and the private sites that I'm apart of.
Like I said, I get a good amout of readership on eFiction, AFF.net and FP.net. I'm happy with that for now.
Oh, piece of advice. When gathering readers, tell those friends you know who will read them. Personally drop a line to those who have been constant reviewers, even when you post an answer to those reviews. It's the little personal touches that brings readers and help encourage reviews.
At least, that's what I've discovered.