I've been reading HN for quite long, mostly parallel to /., then one day I figured /. is no longer for me (I think it may have been one too many instances of browsing at -1 during breakfast or so), so I registered here, a little less than a year ago.
I visit /. very rarely now, the best stuff from there makes it to HN anyway and the S:N ratio is many times higher here than there.
Frankly, I'm amazed it is as large as it is without being overrun by the wild hordes. Apart from one single instance of a downright abusive user ('arrington', a couple of weeks before I joined up) I have seen only very little of that sort of thing here.
I try to keep my 'memberships' to social news sites down to a minimum, I've registered the usual (fb, twitter and so on) but I only really use HN.