Analog vs. Digital Displays

Assuming you are talking about LCD monitors, at lower resolutions, like up to 1280 x 1024, you likely won't see a huge difference between making an analog connection vs. a digital one. These are all the things that are affected by that difference:

Blurriness: You wouldn't think that a fixed resolution device like an LCD could look blurry, but an analog interface can have that affect. Usually, it will be ever so slight at 1280 x 1024 and below, such that most people can't even tell the difference. Above 1280 x 1024 it starts to become more noticeable.

Tuning: Since an analog signal lacks a clock, and since an LCD monitor requires a clock, there is a clock recovery circuit inside the monitor based on a tunable phase lock loop. Monitors will have an "AUTO" tune function, but there are manual overrides for those instances when the auto tune function doesn't come out so good. The manual controls offer a fine and coarse adjust. Tuning is kind of a pain but it's better on monitors today than it was 3 years ago.

Color scale: With digital, the low order byte (0000) equals black and the high order byte (ffff) equals white. Expressed on a scale of 0 to 255, 0 equals black and 255 equals white. Similar to needing a clock recovery circuit, analog interfaces also need to recover the relative highest and lowest levels since they aren't receiving bytes. They can't do so perfectly, so you end up getting a slightly skewed or compressed (or both) scale from black to white. And of course all the colors are affected as well.

That's about the whole list. There is no affect to response time. As for visual distortion, if the clock recovery circuit isn't adjusted correctly, it has the affect of causing a kind of moire in the picture that can affect the appearance of text. Ironically, when a monitor is run from an analog signal, there are usually a lot more user adjustments that are available to the user and active on the monitor through it's OSD (on-screen display) menu system. When you make a digital connection, those adjustments are grayed out, meaning you can't access them.

Well, LCD monitors, whether connected digitally or not, are limited in there ability to accurately reproduce colors. So I think in that case it boils down more to whether LCD is OK for your application rather than focusing too much on the digital/analog question.

Between a 17" and a 19", I personally prefer a 17". They both have the same resolution...1280 x 1024...which means the dots-per-inch (DPI) is going to be higher on the 17" hence to me text and other graphics look smoother without that affect as though you are looking at your image through a screen door. But older people, or people with poor eyesight, tend to prefer the larger text and graphics as found on a 19". I think you need to decide that one for yourself.