I'm a canonslut. I almost always go with canon. I've always been a pretty big Remus/Sirius shipper, so I was disappointed when Remus/Tonks became canon, but I really do like Remus/Tonks, so I go with it. One exception is in CLAMP Campus Detectives; technically Suoh/Nagisa is canon, but I hate Suoh/Nagisa. Nagisa has no personality, no depth whatsoever. She's boring. Plus, I could never actually see Nokoru with anyone else except Suoh, and I can't leave Nokoru all by himself. I always do Suoh/Nokoru.
The whole canon thing is why I always look for evidence for KuroxFai; it just has to be canon, or at least no other pairing that would contradict KuroxFai can become canon, or I really won't be happy. I just like the feeling of having the canon supporting me; I'm not one of the shippers who can and will do any ship they feel like. Nothing wrong with that, it's just not me. Gah, listen to me. We're kinda getting off topic, too. (sweatdrop)