KH is my homepage. In my browser I always have 3 tabs open, one is ALWAYS on the KH forum. The second tab is on a personal site that I always keep open for ease of access, and the third is the one I browse in. In that third tab, I usually go the rounds of checking my email and whatnot, and then I finally sign in to Ravelry. Meanwhile, as I'm browsing, I'm continuously checking in on KH.
I love KH because it is a more intimate setting. If I have a question, I'll ask it here.
However, I love Ravelry because of the way it lets you organize and search. I also like that a lot of groups are for "knitters who love (insert activity or craft)." For example, I belong to a group for knitters or crocheters who love to cook.