If you don't need astigmatism correction, spherical contact lenses give much better image quality than glasses. You don't get the image minification/magnification that you get with glasses, and the off-axis optical aberrations are much reduced because the lens moves with your eyeball, meaning it's always correctly aligned.

Astigmatism correction in contact lenses sacrifices some image quality (sharpness is reduced), but it might still be better than glasses depending on how much correction is needed.

It's possible to combine spherical contact lenses with cylindrical glasses, which might give the best overall image quality depending on the exact correction needed.

Related to this, different glasses lens materials cause different levels of chromatic aberration, measured by Abbe number. The cheapest (PADC, e.g. CR-39) is one of the best you can get.