General monitor advices
Display devices with an aspect ratio of 4:3 are best suited for a proper DOS and early Windows gaming experience. Although widescreen monitors were existent at that time, they only started to become prevalent in the mainstream consumer market around 2005, so most games up to this point were optimized for 4:3. Although such games can be played on a modern 16:9 or 16:10 monitor, one would have to deal with either playing in a window, stretching the image or black bars. Games with real widescreen support were extremely scarce. Although some early resolutions such as the common VGA Mode 13h 320x200 come close to widescreen, they will most likely not be recognized by modern monitors as such (see below).
CRTs are overall preferable as authentic visual interface, even if they have the problem of taking much space and are not built anymore. They support nearly all exotic resolutions that were frequently used in the DOS days, tend to blur rough edges and dithering, and don't suffer from image quality penalties from scaling lower resolutions as much as LCD monitors do. Monitors with resolutions up to 1600x1200 and refresh rates of at least 85Hz are optimal. Early EGA cards have a 9 pin Sub-D connector with a digital RGBI output. This requires a CRT with RGBI input as the later VGA CRTs support analog RGB only.
Decent LCD monitors started to appear in the mass market in around 2001, at first commonly with 1024x768 (15") resolutions, which is already high enough to take advantage of late 90s 3D accelerators. Later 17" and 19" 1280x1024 monitors are 5:4, meaning the image will be slightly jolted when running 4:3 resolutions, but this is far less noticeable than the stretch on widescreen displays. LCDs have the obvious advantages of taking less space and putting less strain on the eyes on lower refresh rates. When choosing one of these, one should look for monitors with response times optimally not higher than 25 ms, because otherwise ghosting in fast games will be very noticeable. Also, good scaling performance is important for low-res DOS games.
Many LCD monitors from the recommended time period already have digital DVI inputs that can provide better image quality than the analog VGA input. Still, using DVI is not recommended for DOS games because refresh rate issues may appear where VGA modes run at 60 Hz refresh rate instead of 70 Hz standard. A typical indication are speed and/or sound issues in games and demos that use the refresh rate for time synchronization. A major disadvantage of LCD monitors is the inability to display certain more exotic resolutions, resulting in a black screen, flickering or discharge patterns of the LCDs output logic.
Most LCDs allow more modes than existent in the list they report to the graphics card. The cause is that technically the limiting factor of a LCD is the supported range of horizontal frequency and pixel clock. Therefore lower refresh rates than the usual reported limit of 60 Hz are possible at higher resolutions. This is interesting for a stutter free representation of old gaming consoles either by emulation or by TV card input at 50 Hz. Setting such mode usually requires to define a custom resolution for the graphics cards driver or by using a third party tool.
If the TV output of a graphics card is used, the refresh rate issues as described in the LCD section may also appear. Usually a setting to PAL standard defaults to 50 Hz and NTSC standard to 60 Hz.