i love panasonic plasmas but the one you posted says 1080p but the specs say 1024x768, but it may be only for the pc input, however it doesnt say the rez of 1080p 1920x1080. seems kinda fishy to me. this one also has 3hdmi inputs compared to the pioneer
the panasonic has contrast ratio of 10,000:1 compared to pioneers 3,000:1
but from the website info it seems pioneer has more features. i would take the panasonic because i have had good experiences with their plasams
btw heres the link to the pioneer specs
PDP-427XD Pioneer HD Ready Plasma TV - Plasma