Hi Wilco74, I've just gone through the same process, with same TVs - tough decision isn't it!
There are a number of good threads on this on this forum. For me it came down to price vs features. The general opinion of the threads is that the PZ80 is the best value. Especially as you can get it at the moment from John Lewis at £699 (price match from the Glasgow shop) with 5 yr guarantee and free delivery.
I wrote off the PZ85 as the main feature on this was discredited by others and those that owned it usually turned it off (can't recall what it's called without looking it up ITC or something -sure someone will correct this

).
The PZ81 does have some good features with the Freesat receiver and Picture in Picture etc. and was a great deal before Christmas (I believe it was at John Lewis for £799) but no longer at well over £1000.
In the end I decided that with the good deal going with Sky HD at the moment; £49 for the box, free install and £50 M&S vouchers - if bought online before Feb 4 -(particularly if you go through topcashback and get the £100 cashback), that I'd go for the PZ80 and forget the FreeSat receiver (can always get a separate box later).
If you go on to the Panasonic site you can compare them all side by side. To add to your confusion (sorry!) if you can wait until march there are some new models coming out
Best of luck and do tell us all what ypou did in the end and how happy you were with it.
Dennis