Panasonic and Oppo are both "top 'o the heap" choices and then it boils down to features. However, you might also consider a PS3 if some of things it offers beyond just BD capability appeal to you. It does an outstanding job with BluRay to boot.
The PS3 will do Dolby True HD and DTS-HD Master Audio, there will be differences between the two models of the PS3( Slim or Fat).
The Fat model will not bitstream these formats via HDMI you have to let the PS3 decode these and then send it to the AVR which will show on the display as Multichannel. The Slim will do bitstream via HDMI and the display on the AVR will show True HD or DTS-HD MA.
Do not go where the path may lead, go instead where there is no path and leave a trail. -Ralph Waldo Emerson
I've had my share of problems with the Panasonic line of Blu-ray Players. I use mine quite a lot. The BDP-30 lasted the longest, about 2 years before getting too sluggish for me in the disc transport. Then the BDP-60 (went through 2 units of this one) would occasionally, about once a movie, stop, go to main menu, then resume playback where it left off. (One unit with latest firmware update, the other with original, same problem.) Then the BDP-210. The motion sensing open/close feature was always a work only sometimes thing. Then the disc transport started getting sluggish and slow.
No thanks. Bought a Sony this time. May not be any better, but at least it's not a Panny.