If you have followed my previous posts, you would have narrowed down your choice of a HDTV. There are other features that you may want to consider before making the final decision.
The more the merrier. Make sure there are enough HDMI inputs to connect all your intended equipment with HDMI outputs. Normally you will need at least 3 (depending on your set-up) - one for you cable/satellite TV box (like Astro), another for your DVD/BD player and the third one for your gaming, camcorder, HD Media Player and other gears. If you have the newer AVR, then this number is not so important since you can connect most of your gears to the AVR HDMI inputs and with just one HDMI cable out to the HDTV. If your chosen HDTV do not have the number of HDMI inputs required, you just have to pull the cables in and out when necessary or maybe you can get one of those multi-HDMI (many in, one out) adaptor.
To connect your DVD player or other gears without HDMI output, you will need either the composite terminals (red, white, yellow) or component terminals (red, blue, green). Most HDTV will have both these inputs, otherwise choose the one with the component inputs since this will give a better picture on the HDTV. S-video input is now less common.
You will need this if you intend to connect up your PC or laptop. Most if not all LCD TV has this, but for Plasma need to double check. You should go for a Full HD model if you want to hook up a PC or the lower resolution will show up.
USB and Memory Card slot
Some models have a USB slot to connect a thumb drive or external HDD to play music, photos and videos but the video files format support differs from model to model. Some have a Memory Card slot (like Sony and Panasonic to support their cameras and camcorders directly) for you to view photos and videos. Personally, I feel it is better to get one of those HD Media Player which is more versatile and has more functionalities then the ones built-in with the HDTV.
Plasma screen usually reflects more light while LCD are normally matte but newer models are more glossy so you need to pick the one that best suits your viewing environment. Too much reflection will spoilt your viewing enjoyment.
LCD can never beat Plasma in this area. All LCD TV will have a smaller viewing angle than Plasma but this differs depending on the make. Look from the sides of the LCD TV to see how bad the image is affected but in practice it is not critical since most of us will be watching from the front and not too much from the sides of the TV.
Cinema Mode, 24p
This is also called Real Cinema, Real Movie, etc. by some brands. Movies are shot at 24 frames per second (24p) while the normal rate for videos are 30 frame per second (30p) in NTSC or 25 frames per second (25p) in PAL. So to get the right movie feel, some HDTV have this 24p cinema mode. Note that this will only work if the source is also output at 24p and Blu-ray Disc players can do this. Like in many other features, some models of HDTV can do it better than others. To most people, the improvement is slight and many people cannot see the difference unless the two rates are displayed side by side. So this is more for the purists and videophiles.
Generally, the bigger the set, the better the sound and the higher end models will sound better than those at entry level. But really, to complement the HD video, you should hook up an AVR to enjoy the HD sound, especially from Blu-ray discs for a complete enjoyment of HD.
Calibration enthusiast may want to check what parameters are available for tweaking. All HDTV will have enough video/colour adjustments provided than most of us can handle.
If your already have equipment from a particular brand, you may want to consider the advantage of getting the HDTV of the same brand (if the critical specs meet your requirement) such as using one remote control for all the equipment.
WiFi and Internet connectivity
Some higher-end models may have these functions. Only you can decide if you really need these, at a cost.
Finally, there is the physical built and how the HDTV looks and blends in with the rest of the furniture. For that, we better leave it to the wife or mistress, oops, I mean the missus.