How the lens behaves to film is pretty much how it behaves to the groundglass. The groundglass tends to spill points of detail a little more than film. A really sharp lens image is going to look good. A softer image may look a little softer than it would appear on film.

The best of my lenses is the 85mm f1.8 Nikon autofocus, then the 28mm f1.8 Sigma autofocus, then the 20mm f1.8 Sigma autofocus. The worst one but also the oldest and most worn out is the 50mm f1.8 Nikon manual.