Best monitor for the Sims 4 gameplay?

@Dreamspinner3  There are a couple details that matter here: the size and resolution of the monitor, and the refresh rate you'd like.  These will determine the options in your price range, although you should be able to get something good enough regardless of the specs you want.  Without knowing those details, it's difficult to make any recommendations.

If you want to play at a 2560x1440 resolution, you probably won't see framerates a lot higher than 60, maybe consistently in the 70s but probably not worth the extra expense of a 144 Hz monitor.  Even at 1920x1080, you might only see 100 fps for part of the time, although that still looks better to a lot of people than 60.  (If you'd like to see how your game performs now, you can enable the fps counter through Origin in-game or use the cheat fps on to show it.)

Once you know those details, it's easier to get an idea of what specifically you should be looking for.