Ah, the choice between two fantastic technologies. I tend to research the crap out of stuff like this before I buy it, but I’ll try to keep this post simple and short.
My vote is LCD unless you’ll have it in a darkish home theatre room that has few windows. I bought a Samsung LN52A650 (LCD) about a week ago. I’m pretty happy with it so far, other than the RSS/weather only supporting USA, (some US models support only Canada) and I think the menu overlay animation is slow and choppy. Also, having 2nd gen 120Hz processing, I expected more out of the feature.
I picked LCD for two reasons. The first was because my living room is fairly bright, having 3 large windows. Secondly, I might eventually hook an HTPC up to it. LCDs generally display a desktop, etc a lot better than a plasma and do so without the risk of burn-in, though all new plasmas have an etch-a-sketch sort of thing you can run to ‘cycle’ the screen through black, white and grey.
That said, if you’re still thinking Plasma… It does offer better picture, color, and value. LCDs and even more so, LED LCDs cost more when you start looking at big sets, and they don’t give as accurate a picture, though the LEDs sets are pretty amazing. A plasma is probably more child-proof since the entire front is glass. You can poke at, break, tear or scratch the surface of some LCDs.
If you’re willing to spend on an LED backlit LCD, be aware that there are two types, edge and direct. Edge is more common right now, but my guess is that as direct becomes more available, the edge sets will drop a fair bit in price. Direct is better, having an array of LEDs behind the panel, vs having LEDs at the edge being projected onto the back of the panel.
OLED is also just around the corner, and will blow away any form of plasma or LCD. I imagine they’ll be very expensive.
Really though if this is your first HDTV, any option will leave you impressed.