I have tested with both HD and SD signals on both TVs.
I took a normal HK Drama (650MB) and a Planet Earth (2.7GB) to be played on both of the TV own built in Media Players

The comparison that i notice is as of below:

Panasonic
HK Drama: Playback started successfully. The picture was pretty smooth and very less boxy edges noticed even at the side curved lines. Picture and color is much softer compared to Samsung (based on Dynamic setting).

Planet Earth: Playback started successfully. The picture was very smooth. Color is rich and pictures are sharp. There was some juddering of the playback at the start but after i skip that section, the movie continued playing normally.

Price: RM2,850

Samsung:
HK Drama: Playback started successfully. The picture was pretty smooth as well but more boxy edges was seen throughout the picture. Picture and color were much brighter compared to Panasonic (based on Dynamic setting)

Planet Earth: Playback didnt started successfully so i could not provide comment on this. The message says the codec is not supported. Firmware issue i guess.

Price: RM2,950