I like iModeler.
I joined in April mainly because:
Its easy - I really liked the 'steps 1, 2, 3' at the top of the front page. Shoot that's so easy a dumb ol' hillbilly like me can do it.
The whole interface is easy to follow, easy to browse and encourages visitors to stay.
I've looked at the Hyperscale page and found it complicated and overly commercial. The thread format is not inviting like iModeler and I just am not patient enough to dig into it much. So I haven't experienced the snarkiness there I read others have been exposed to. The site itself hasn't encouraged me to want to post anything or participate, though I am sure there are lots of experts who could tell me exactly how many frutinator springs my model should have and where they go...
Now granted I see some fantastic models posted there. But I see fantastic models posted here too...which brings me to another reason I like iModeler...I feel warmly welcomed here, despite my 'newbie' status and imperfect, beginner level models. Some folks who post here are truly experts in model building and they awe me with their craft - but all the critisisms I have recieved have been constructive and helpful, and offered with humility. I mean, heck people who know way more than me are almost apologetic in offering advice. I like that aspect and have learned a lot from those responses as well as just looking at what others have done and reading about how they did it.
iModeler is website I just enjoy looking at. The owner/author/creator/administrator gets two thumbs up from the kid here.