The 609 is in theory the higher model so should give better sound quality. what speakers do you have?
The Denon 1912 and Yamaha 671 are also the same level as the 609 and have been selling for cheaper but are very hard to find but still worth a look. Also the Yamaha A810 is around the same price as the 609 but another level up so could be even better value.
I've got Wharfedale 10.3's and 10.1's. Which is going to be best suited for them? To be honest I really like the look of the 671 and can get it for £50 cheaper than ther 609 so that's a bonus. Whats it like for sound?
The 671 is comparable to the 609 for sound quality. However, both the 671 and your current speakers are often described as being warmer sounding so may not be the best pairing. That said, there are many people with the same combination that are happy with it so it really comes down to personal sound preference. What is your current receiver?