I would like to purchase a large screen (monitor) for my coding, i.e. no gaming, no video, no tv, just text editors. So my question is, I am looking into buying a 40" LCD TV and am seeking the sharpest viewing for text. Does 720p over 1080p make a difference? The price differential is quite a lot between the two it seems. What other key features should I be looking for in LCD TVs that I want to use as a PC monitor for text rendering?
Do yourself a favor and get a real monitor. The pixel density and resolution will be much better than an LCD TV. Since you're not using it for gaming or content consumption, you are purchasing a very large and mediocre display for text / computing screen elements.
If you have a grid of 1920 x 1080 across 40 inches on a screen, the individual elements "pixels" will be much larger than the same grid of 1920 x 1080 on a 24" screen. Each pixel is more pronounced on the 40 inch screen and text will appear fuzzier than on the 24" screen.
Also, if you're sitting at a desk with a display this big, it will reduce your productivity. Studies have shown that you are more productive with 2 monitors vs 1. There is also a point of diminishing return on monitors over 24".
NPR Article about University of Utah Study on Monitors - one of many that have a similar conclusion.