So I have more than 30 computer monitors that came from auction batches that I purchased for resale, and I'm considering keeping one of them to replace the CRT monitor from 1999 I currently use. Dells, Samsungs, Acers, and HPs. I know there are pros and cons to CRTs and LCDs, especially for gaming, does anyone have a personal preference for the purposes of The Sims 2?

If you can set the game to the native resolution of your flat LCD monitor, then it will look good. Sometimes the native resolution is not easily accessible on monitors that are sold as TVs. A really big monitor may need more power than the computer has to drive at the native resolution.

The appeal of CRT monitors is with older games that only offer one or a few lower resolution options. This causes upsampling, which makes sparkly things like gemstones dull. Such things occur mainly with hand-drawn assets instead of 3D, which always get stretched out. A CRT can, within limits, smoothly adjust the pitch between lines instead of matching fixed pixels.

CRT monitors have a low life expectancy. I would save them for retro gaming.

I have always used an LCD monitor with TS2 and it looks and runs just fine. The details are sharp and crisp as they should be. TS2 actually supports up to 1080p (aka "FHD"). There is little reason to use a CRT monitor nowadays except for nostalgia feels. If you do run an LCD monitor, you'll very likely need widescreen patches for the UI to be adjusted to the higher display resolution properly. But it's a small thing that shouldn't discourage you from upgrading.

The game was originally designed when the default monitor display size was 800x600 and 1024x768, so CRT would be the optimal solution. While LCD monitors offer a crisp and sharp display, a larger screen tends to stretch the image more. You'll especially notice the lower quality in the Sims skins, the grass, and clothes in a vanilla game. CRT Monitors are also recommended for older games because the blur is hidden through the interlacing, dithering, and the lighting giving off a special glow. This makes Sims 2 look even more fantastic, and it is not just from nostalgia. This article (content warning on 2nd image) has some good examples of games looking better while played on a CRT. It's why I keep my old CRT TV along with my HDTV for classic and modern games.

However, that's not to say avoid LCD/LED monitors altogether. Other than installing widescreen patches and default replacement textures, you can also enable CRT filters with ReShader for Sims 2 to recreate the original look on an LCD monitor. That's how I presently play this game, increasing the saturation, smoothing the textures, and even using some of the CRT filters. But it falls down to your preference, using a CRT Monitor will require less work in the display department. Whilst with current monitors you will need to download some patches and tweaking the effects of ReShader to perfectly replicate the original look. If anything, I would recommend looking into an OLED monitor since they're a step above LCD with displaying graphics but are on the pricier side. Still, there's workable solutions either way.

You can find a smaller LCD monitor on the used market if you have a need for 1024*768 resolution, like the SDM-S53 that I have. On more modern screens the pixels are smaller and they offer incredible crispness. In a 3D game, a patch of grass or whatever is always stretched depending on how close it is to the camera. For the most part, all textures in this game have a size reserve where they are always scaled down in typical viewing situations.

Another property of an LCD monitor is the black level. I didn't mention it because it seems that most new (large) monitors these days are IPS or PVA, which have good black level. This game is also not dark like horror games where it matters more. Unfortunately, when an FD Trinitron nears its end of life, its black level also for some reason rises yielding even lower contrast. Usually the red color increases and you need to bring up the others to compensate. When I replaces it with an LCD it felt like taking off a veil.

"Interlacing" is not a correct term to use. That is applicable only to broadcast video. Computer monitors have progressive scan. What you might thinking of is the scanline effect where a pixel is drawn as a horizontal line with some darker space between the surrounding rows. "Dithering" does not happen in CRT monitor. It means an addition of noise to make more color levels available.

The article talks about "TVs" like a 21'' television or probably even smaller in the living room that you viewed from a few meters away. A typical computer monitor doesn't have such coarse elements that you could see with a naked eye.