Chris
Welcome to the forum. I have an Onkyo 905 and had a demo of a Pioneer lx55 but it did not do anything for me or my son. When we were buying a B&W Zeppelin for my daughter we heard a Yamaha recever and wow it made movies and music fun and real pleasure! So if my Onkyo died I would definitely audtion a Yamaha. I have a Denon Dvd player and its built to last and I love it.
You don't mention any speakers but must have them with your Onkyo 606. I would audition a number of manufacturers within your budget just to ensure they have synery with the rest of your system. I know that lots of people on the Forum have Pioneer receivers and love them.
Best wishes
Chris