Re:
bear in mind i have to clean chains at the shop,
i use an ultrasonic cleaner (bought from ebay), about 40degress for 20 mins in a mix of water and Fenwicks FS1, chain comes out still looking a little dirty but then a light brush in my cleaning bath after and it's mint, especially if it is a quality plated chain. the bonus of this is while the chain is cleaning i can be doing other stuff. then i leave it to dry, refit to the bike and lightly lube the chain.
for at home, the Park tool chain cleaner is excellent as is the Muc-off chain cleaner, both £30 RRP but you can find them for less, i prefer to use proper degreaser as opposed to some of the suggestions of paraffin etc, the Fenwicks FS1 is my preferred degreaser because i use it as a concentrate in the chain cleaning bath and watered down for the rest (which makes it FS10).