Monitor
Throughout the DOS era, CRT (Cathod Ray Tube) screens were the norm - LCD (Liquid Crystal Display) screens were not introduced to the wider market until the latter half of the 1990's.
Again, the choice is down to compromises, as both screen types has advantages and disadvantages. If you are a purist, a CRT is the way to go, but...
CRTs are big, bulky and heavy. The are often flickery, as they usually run at 60 Hz refresh rate. Stable, non-flickering images can usually be achieved at around 75 Hz, but the higher refresh rate often came at the cost of resolution - higher resolution, lower refresh rate.
Finding a CRT in good, working order today (for a decent price) is more or less impossible, as they usually loose some of their crispyness and brightness with age.
On the plus side, they do display clear, warm images. While CRTs do have a maximum resolution, its pixel-size are not fixed as with LCDs. This means that it can display resolutions lower than the maximum without interpolation, as it more or less changes the pixel-size to match the lower resolution.
LCDs, as you probably know, are far easier to place on the desk. Due to the way they display the image, flickering is not a problem, and you can easily look at a LCD with 60 Hz refresh rate all day long, without tiring your eyes (provided you don't set the brightness to high).
The problem with LCDs is interpolation. It is not as pronounced today, as it is less visible, the higher the native resolution the screen has. But for a DOS machine, you want a 4:3-format screen (a 5:4 is also acceptable), which limits your choice of resolution.
While you may be lucky to find a 1600*1200 LCD in decent condition, it is more likely that, if you choose an LCD, will end up with something along the lines of 1024*768, 1280*960 or 1280*1024 (the latter being 5:4 aspect ratio).
Lets take the 1024*768 as an example. This is the monitors "native resolution," meaning that the screen has 786.432 pixels - 1024 columns and 768 rows. If the screen gets a signal in the resolution of 1024*768, no problem - it will just display that. If it gets a signal of 640*480, all hell breaks loose!
Now, to make the image fill the entire screen, the screen will resize it to 1024*768. This becomes a problem, as this means each pixel of the original image now has to be 1,6 "native resolution-pixels" wide and high! But, as the LCDs pixels are fixed, two original pixels will be stretched to three pixels on the screen (actually 3,2), interpolating the middle one between the two.
Imagine the first pixel is black and the second is white. When interpolated to three pixels, the middle pixel will become a 60% grey. And the fourth pixel will still contain 20% of the original pixel twos color, regardless of the fifth... And this is not just horizontal - the same thing happens vertically!
As you might imagine, it can pretty quickly look horrible. Some older monitors (and IBM laptops) have a function to not interpolate the image, but to just display the original resolution with a black border.
This doesn't mean that it is always a problem. Displaying a 640*480 image on a 1280*960 panel is no problem at all, since 1280/640 is 2 - and so is 960/480. In this case, each pixel will just double and be shown as 4 pixels (2*2) on the screen.
I recommend
My recommendation here: Get a monitor that suits your needs! I cannot recommend just one model. Personally, I'm using a Dell 1907FPc, a 19" SXGA (1280*1024) 5:4 aspect ratio TFT LCD monitor which, according to the sticker on the back, is manufactured in October 2006. I have only once experienced that it reported a resolution out of range (trying CubicPlayers eXtended mode), and you do sometimes need to reset it (turn it off and on or switch the input) to make it sync properly to the input signal, but it gets the job done. Another benefit is that a LOT of companies used these back in the day, so they are dirt cheap still. I got mine from the dumpster room at work.
