PQ wise there simply isnt IMO, to get close you need to spend on a full array LED. There are pros and cons to both tech but even the experts agree pound for pound plasma has better PQ. LCDs inc LED back lit cost a tad less to run, can go brighter and dont get IR. On the flip side LCDs esoecialy edge lit LEDs have uniformity issues as standard and back light bleed. LCD cant compete with plasma on motion or black level, some LEDs can go blacker by turning off parts of the picture, this means they cant produce the same level of shadow detail(darker part of the picture) and when lighter areas of the picture appear the black level goes up. all LCDs also have viewing angle restrictions(some are a lot worse than others)
At 40" and over LCD has lag problems and is higher than plasma. Full array LED sets use an array of LEDs behind the screen, this makes a huge improvement PQ wise but the sets still arent per pixel lit so cant creat the same level of detail as plasma in the dark part of the picture ir the lightest, they can also suffer haloing around objects.
Plasma isnt for everyone though due to IR, limit on brightness, cost of running and for some plasma trails and flickering.
Active v passive 3D. Active on LCD has bad crosstalk, best to go passive on LCD as theres no crosstalk. Active on plasma has little cross talk, Panasonic have very little. Active flickers under strong lighting, dull or dark room(home environment) flicker isnt an issue really(from personal experiance).
Passive glasses are cheaper but passive isnt 1080p per eye(the differance this makes is hotly debated, Im on the fence) thoygh a lot of 3D isnt even 1080p anyway. Passive is also only available on LCD.
Just to add there is one maybe two alternatives to the GT30 plasma wise and thats the Samsung D6900 and D8000, worth looking at. Read the reviews on here to compare and then go see.
