Only way to tell is to demo both tv's yourself and see what suits you best. Make sure that whatever tv you test is properly calibrated and view both SD and HD content.
I have the 42PZ85 and I think it's a very good tv, good with SD content, upscaled dvd's through PS3 look fantastic and Bluerays take your breath away. Even the sound is pretty decent by flat screen standards. Especially the BBE VIVA 3d virtual surround mode. Very good with fast motion and very natural colour reproduction, good black levels as well. Even the remote is decent, simple well laid out controls.
I havn't seen the Sony with my own eyes although the team rate it very highly. Like I say you need to view a few tv's and see what you like the best. Some prefer LCD's and some prefer Plasma only you can decide whats best.