I have the 42PZ85 and it's a very good tv. Good with SD, very good with upscaled dvd's through the PS3 and absolutely stunning in HD. Games look amazing, and the very fast response time really makes a difference with fast action games. Really smooth with fast panning shots or football for example, very natural colour reproduction and even the sound is very good by flatscreen standards. The BBE VIVA 3D fake surround works really well and sounds as good as normal stereo but with added surround soundiness. Very good remote and it comes with a swivel stand which is really handy. Also the picture looks almost 3d even with SD content. Just wait until you watch a blu-ray in 1080p, big big wow factor.
Negative points are the onboard digi tuner looks a little bit softer than SKY, although not by very much. And it does take a bit of tweaking to look it's best, the factory default settings are miles off. 10 mins with the THX optimiser works wonders. And the "IFC" feature can make fast action like football on sky look very weird, the ball will suddenly disapear and then reapear further up the pitch. Turn it off in the tv menu and it's perfect. (It's turned on by default on all the tv modes btw)
I havn't seen the new Sony's so I am not sure how they compare. I love my plasma though.
Best option is to view both tv's and see what you prefer, make sure to view SD content as well.