What desktop computer should I buy to play sims 3, sims 4, and minecraft?

I don't know

I play all of these on a cheap laptop, so I say it doesn't really matter much, and the lag probably has to do more with your internet speed. But I don't know much about computers.

Check out CyberPower PC or Ironside PCs. I I'm only throwing those names out their because if you want to move on to playing other games those PCs are good for most games.

You need:

1. An i5 or better processor. You could get away with an i3, but Sims is CPU intensive.
2. A video card that can push good graphics, made by either AMD or nVidia.
3. 8GB of RAM if running Windows 10.

For what you are doing, pretty much everything else is optional. If you buitl it yourself, this could be at or under $500, but it'd retail around $800-900.