I'm keen on ER, but often there's frustratingly little of the exciting diagnosis of mysterious diseases part, and a lot of dull 'relationship' stuff. However, in ER I can (at least some of the time) correctly diagnose the patient's problem before the doctors do, which is something I can never do with House. I've tried guessing Lupus erythematosus a few times, purely on the basis that it's obscure, has lots of interesting symptoms and cool name, but with no success so far.
I love the whole House/Holmes, Wilson/Watson thing, and House is paradoxically a very appealing character. He's so even-handedly horrible to everyone, regardless of age, race, religion or gender, that he somehow manages to be perversely charming. Mind you, if he was my doctor, I'd make sure I was never ill.