I'm pretty faithful. I think I've got an account on some playstation forum which I use for trophy guides, but I'm not sure if I've ever posted anything. Certainly nothing noteworthy.
I used to use Digital Spy a bit, but I much prefer it here. Probably overgeneralising, but I find that DS seems to attract a certain demographic of disillusioned , middle aged men in particular, and that it has a rather pessimistic vibe. It's also extremely argumentative, with people challenging pretty much everything. You could post something like "I don't like killing kittens" or similar, and you'd instantly have people starting up a counter-argument. I found it all a bit draining. Nothing wrong with a bit of healthy debate, but the good old British pessimism is rampant there. I also dislike the grammar nazis who get aggressive even if people explain they are dyslexic, etc. It's also a little fanatical in certain places, like the Doctor Who forum. I'm a fan of the show, but I don't spend hours analysing every single plot development. On the flip side, the music forum is rather vague.
Sometimes Popjustice has some interesting stuff, but the forum is very gaudy looking and the signatures etc are annoying, so I've never joined. I also find they open threads with no sources or confirmation whatsoever. At least here, the information is pretty reliable. In truth, there's nowhere quite like UKMix.