http/www.hometheater.com/content/how-choose-flat-panel-hdtvs
LCD, and Plasma each have unique benefits, advantages, and weaknesses.
Generally LCD is better suited for a bright room. They are often the choice for gamers, or people who use them as computer monitors. LED backlit LCDs have very vibrant color, and bright images. LCD relies on a refresh rate to reduce image blur/smear. They are much better than the past, but a keen eye can still pick up on this.
Plasma is regarded as the technology for movie buffs. They are capable of better shadow detail, and accuracy than most LCD sets. The gap is closer than it has ever been, but Plasma still edges out all but the very top of the line LED local dimming sets. Plasma sets have a glass front, so daytime viewing in a bright room can be a challenge. Extremely fast motion is better on a plasma as well, as they do not rely on the same refresh rate as LCD.
Honestly, the best thing to do is take a read of the article I linked, and go look for yourself. Most people will prefer one over the other, but there is no right answer. I personally own two Plasmas, and an LCD. I much prefer watching movies on my plasma sets, but like the LCD for daytime viewing, because I can see it in my brightly lit living room. One thing to remember, manufacturers love to turn their sets on "Nuclear hotter than the sun mode" in the showroom. This grabs your attention in the store. LCD will almost always win the brighness battles. Make sure to evaluate your choices with different content, on normal baseline settings, and if posisble, different lighting situations.
Edit: Forgot your brand inquiry.
For LCD, I feel LG is a very good value price/performance, but if you're willing to spend more money, you start hitting Sony's HX/XBR line, or samsung's 6000+ series, they really start to pull ahead of LG in terms of image quality. For Plasma, Panasonic all around would be my first choice, which is good, because they're the only manufacturer currently building 42" sets.