Samsung UN55D8000 vs. Sony XBR-55HX929
Actually, $3500 for a 55-incher is starting to get into ultimate territory these days, though of course, you can spend a lot more. Generally speaking, Samsung makes excellent LCD TVs, including its flagship UN55D8000 (reviewed here and shown on the left above), which lists for $3600. However, none of Samsung's models use true LED backlightingthey use LED edgelighting, with LEDs along the edges of the screen. This allows the TV to be very thin, but it typically causes the illumination of the screen to be uneven, especially in dark scenes, which is the only reason the UN55D8000 did not get a Top Picks designation in our review.
With true LED backlighting, the LEDs are placed in an array behind the LCD panel, allowing a feature called local dimming, in which the LEDs behind dark portions of the image can be dimmed while the LEDs behind bright portions can be brightened. This results in much greater perceived contrast, though it can also cause halos to appear around small bright objects on an otherwise dark background.
These days, the only major companies that make true LED-backlit LCD TVs are Sharp, Sony, and Vizio. The new Sharp Elite models are most likely the best of the bunchwe haven't reviewed one yetbut they are way beyond your stated budget. Sony's only such models are in the top-of-the-line XBR-HX929 series. The 55-inch XBR-55HX929 (shown on the right above) lists for $3800, but the last time I looked on Sony's website, it was reduced to $2970. That's a great deal on a superb TV, which is reviewed here as one of HT's Top Picks.
If you have an A/V question, please send it to firstname.lastname@example.org.