All else being equal, a receiver with THX algorithms sounds better for home theater than the one without.
Now of course a $4K non THX Denon will sound better than a $600 THX Onkyo, but what's the point?
THX unfairly gets a bad rap. Especially from fanboys who cant afford their certified equipment and have to justify their purchase to themselves somehow. THX is a very legitimate organisation, which enforces a certain quality standard. Yes, they make money. But it's a business like any other, nothing wrong with that