When you configure a group of adaptive streaming files, you produce some files at relatively low data rates. With these files, you have several options to preserve quality, including lowering the resolution, the frame rate or both. Lower resolutions preserve frame quality but can look pixelated when scaled for display. Higher resolutions avoid scaling artifacts, but frame quality can suffer. Dropping the frame rate preserves smoothness, but drops frame quality.
Below you can see the same source video encoded at 5 configurations, all to 300 kbps. These include:
As you can see in the screen grab, they’re all roughly the same size.
Have a look and see which one looks best, and if you have a strong opinion, let us know via a comment.