My 2 cents on the issue. I'm by no means an expert, but I have been asking advice on the same thing when I was looking at TVs
First off, 60hz, 120hz, 240hz really only applies to LCD/LED TVs. The beauty of plasma is that the picture is projected almost instanteously while LED/LCD requires the individual diodes to turn on and off. Plasmas therefore don't have the problems normally associated with fast motion that LCD/LEDs do.
For just LCD/LED TVs, generally 120hz is preferred for those intent on gaming and watching Sports. However, be aware that it isn't just refresh rate, but each brand has their own motion processor that adds to the smoothness of it. A LCD TV at 60hz but good motion technology can be smoother than a cheaper LCD TV at 120hz. Right now, 240hz appears kind of over kill and the differences are too subtle for most people. Also, it can predispose some people to epilepsy
Lastly, the LCD vs Plasma
At the very top end, Plasma with beat LCDs in overall picture quality. They have richer colour and "True Blackness"
However, at the mid and low end, LCD has made significant gains to narrow the gap. In my humble opinion, the average LCD and average Plasma can have just about the same picture quality in their ideal conditions.
Things to consider:
- Plasma burnout, while still an issue, has pretty much been minimized and you won't have an issue with normal usage
- Plasma works best in dark rooms with little light. Even with antiglare technology, LCDs have better picture quality in rooms that have ambient light than Plasmas do
- Plasma is more delicate than LCD and harder to move. You can't lean them more than a certain angle or lie them flat without damaging the array inside. Plasma TVs are always shipped upright. This is important if you plan on moving it around
- Power output favours LCD, but Plasma power consumption has been greatly reduced
- In terms of market, Plasma is slowly being phased out to LCD TVs. Panasonic is getting out of the Plasma business although Sharp and Sony continuing to produce them. This may affect parts and repair