@superfam04 As far as in-game framerates go, it's hard to say what the best option is for you because some people can't tell the difference between 60 fps and higher. Others can and would prefer to play with higher framerates. But if you're used to 60 fps and are fine with it, then a 75 Hz monitor should work great. Additionally, a higher-resolution monitor, either QHD (2560x1440) or 4k (3840x2160) would be a significant step up as well. I don't know what size you want the monitor to be though, or even if you have one picked out; if you don't have one in mind, let me know either the size you want (measured on the diagonal) or the width you'd prefer it to be.
For the computer itself, I found one option that's priced significantly below what I'd expect, with a very new, very fast graphics card that should easily run Sims 4 in 4k at 60 or 75 fps. (This card is about 35% faster in gaming than the 5700XT.) The processor is not overly powerful but is more than fine for the game, and the motherboard socket it uses would support a CPU upgrade if you decided you needed one for other reasons in a few years. Its other components are all good or great quality, as good as or better than what you'd find in a prebuilt PC from a typical manufacturer.
https://www.cyberpowerpc.com/system/Gaming-Instant-Ship-GM-99577
It does only have 500 GB storage; while that's more than enough for most people, it kind of sounds like you might be looking for more than that. If so, you could easily add another drive yourself, now or later. But if you don't want to need to do that, there aren't any other desktops with as fast a graphics card in the same price range; the next cheapest one I found is this, for $1,400, with a 1 TB SSD:
https://www.amazon.com/Skytech-Shadow-3-0-Gaming-Desktop/dp/B08R45ZC6Q
To be clear though, you don't need such a fast graphics card for Sims 4, and in fact if you're planning on playing on a 1080p monitor, it would be a waste of power even at 144 Hz. For 60 or 75 fps, something with a 1660 ti or Super would be perfectly fine and likely not run particularly close to its max workload while you played. For example, these would work:
https://www.amazon.com/CyberpowerPC-Xtreme-i5-10400F-GeForce-GXiVR8060A10/dp/B08FBK2DK5
https://www.bestbuy.com/site/cyberpowerpc-gamer-xtreme-gaming-desktop-intel-core-i5-10600kf-8gb-memory-nvidia-geforce-gtx-1660-super-1tb-hdd-240gb-ssd-black/6430869.p?skuId=6430869
https://www.bhphotovideo.com/c/product/1560350-REG/msi_mpg_trident_3_10si_002us.html
https://www.bestbuy.com/site/lenovo-legion-tower-5-amd-gaming-desktop-amd-ryzen-7-3700x-16gb-memory-nvidia-geforce-gtx-1660-super-256gb-ssd-1tb-hdd-phantom-black/6424472.p?skuId=6424472
There are plenty of other options; these are just the cheapest ones I saw that are made by reputable companies. In this price range, 8 GB RAM is typical, but it's easy enough to upgrade to 16 GB, which is more than you'd ever need for Sims 4, even with some multitasking in the background.
For the Nvidia 1660/2060 options, it would also be easy to customize a desktop with your preferred configuration, if you'd rather have the extra storage or memory already installed. For example, this Dell is $1,062 with a 1660 ti or $1,152 with the slightly faster 2060, plus 16 GB RAM, a 1 TB SSD, and an upgraded power supply:
https://www.dell.com/en-us/shop/desktop-computers/dell-g5-gaming-desktop/spd/g-series-5000-desktop/gd5090g520s?configurationid=e1c7079a-0cfb-4999-969e-47063be4ac96
https://www.dell.com/en-us/shop/desktop-computers/dell-g5-gaming-desktop/spd/g-series-5000-desktop/gd5090g520s?configurationid=e1c7079a-0cfb-4999-969e-47063be4ac96
I didn't compare the prices for prebuilt systems because there are too many possibilities to cover; you'd need to at least choose the level of graphics card you wanted, then we could go from there. But it's fairly simple to find the cheapest good options with exactly the components you want as long as I know the basics. That's why I asked about the monitor—assuming you'd like to play with ultra graphics settings, it's easy enough to figure out what GPU would max out that monitor.
Anyway, let me know what you're thinking, more or less, and we can narrow things down from here if necessary.