f8500 vs st50
no contest the f8500 wins. it's brighter, blacker, and has more steps inbetween. so it's better in a dark room, and much better in a bright room.
f8500 vs st60
I spent a LOT of time comparing the two in april when I was shopping. imo, it's not a 'clear' winner anymore. I preferred the f8500 because it seemed like it was as good in a dark environment, but better in a bright room. I wouldn't say the f8500 is the better display for everybody though. for instance, I have my backlight set to 12 out of 20 on the f8500, basically bringing the brightness below what the st60 is capable of anyway. I did however feel that the f8500 appeared clearer/cleaner when I compared them directly. it has less space between pixels, which does seem to give it a bit of an lcd look, but in a good way. digital content looks crisp and precise, and film still looks as good as it always has on plasmas.
most ppl however feel the f8500 compares closest to the vt60 or zt60.
F8500 is probably a little bit brighter but ive read that the ST50 can reach pretty high levels. The ST50 reaches 0.002 ftl after 250 hours. They seem comparable to me. But the f8500 has a better light filter.