More accurate colours, better motion, less input lag, much better blacks. They now rarely suffer from image retention. Plasmas offer many advantages over LCD. Their only negative would be power consumption.
Unfortunately when in a department store with terrible lighting, people seem to buy the brightest displays, which are always LCDs. Combine that with sales people who would rather not, or can't explan why Plasmas advantages.
Not to mention that LCD's are cheaper to produce and therefore offer better profit margins.
I worked at a big name electronics store and I was told not to tell people about Plasmas advantages unless the customer was close to buying one. Pretty much the only Plasmas that were sold, were to people who have researched on their own and had already made up their minds.
Everyone else always bought LCD because they look brighter in the store, and side by side, people think the brighter display has a nicer picture.
We were told to encourage this because it confirms their initial impression and often lead to a quick sale. If we told them otherwise, they'd get confused, and leave without buying anything.
I couldn't deal with misleading people, and quit.
The good Plasmas are better for gaming than the best LCDs. Even the 240hz LED displays. So many people have been told the opposite, by authorized reps. It's shameful.