I've used chain cleaners for years with the citrus degreaser made for it. I imagine Simple Green would work just as well. Sometimes I run it twice or more, but most times once. Simple and effective (enough).

I've also done the take-off-the-chain routine in the past but got lazy with the chain tool. Now that everyone and his brother has one of these easy-to-use master links I may go for it and remove the chain for a good bath more often.