Right click, open image in new tab to see full size. I think 1280x720 and 1366x768 are the best 16:9 resolutions for The Sims 1.

640x480

777x777

Non-standard resolutions work in windowed mode too!

1280x720

1366x768

1920x1080

2560x1440

2880x1620

3840x2160