It seemed a pedantic point (and still does) to be upset that a retailer would show how a product can look its best, not its worst.
Yup ... but on the other hand, worth stressing that whatever way you go, with whatever set, RTFM! and get the thing out of "torch mode". The usual default settings are there to make the set look good in a big box store under huge amounts of light. Tricky part is, a lot of sets only allow you to change that in the initial setup when you first get it home, so if you missed that part, you usually have to go back to the beginning, losing any custom settings or whatever, including your streaming subscriptions. DO make sure you note any passwords and such before attempting this.
And ... as mentioned, the plasma vs LCD thing is pretty much moot nowadays. Biggest issue with early LCDs was the horrendous backlighting (think "spotlighting"), but that's mostly gone now. Better sets have gotten away from edge lighting as well, so you've got even brightness and dynamic contrast across the screen. My Samsung Series 7 is pushing 5 years old now (that's like, what ... 100 in TV years? <G>) and I can't say I've ever noticed any such issues, in any lighting, or with any source.
OLED? Eh. I actually prefer SD playback, except for sports. I've got my Dish receiver hooked up in both HD (HDMI) and SD (S-Video), so I can switch res on the fly. IMHO, most movies and such benefit from lower res, and if a game ain't interesting enough to keep my mind off any picture issues, it must not be interesting enough. Then again, I'm only working with a 46" screen in my cottage size house - The bigger the screen, the more obvious any pixelation and other such will be, and the higher quality picture you'll need.
Oh. DO check the speed of the set before purchasing, as that can make a BIG difference for ghosting, motion trails, or other such artifacts. I'd go with at least 240hz ...