This is probably just personal choice, but I moved from a Denon 3805 to a Onkyo 875, because I really liked the THX sound fields. When I use the non THX sound fields, that are all Dolby only, they don't sound quite as good.
I also had the chance to test it against the Denon 4308, and in the particular setting, I liked the Onkyo a little better. But again, I think this all goes back to personal preference.