Onkyo,Denon,or Yamaha for DolbyDigital?

I was wondering if any body here has used either of these three for Dolby Digital and how did they perform SQ wise and which one or ones had the most life like impact? I have an Onkyo that I use just for music and I'm looking to get a D.D. system and need some feed back,these brands are in my budget,which is around $700. Any suggestions?