For a coaxial digital cable, you want a precision-engineered 75-ohm cable with uniform impedance (incl. connector) to ensure accurate signal transmission and to prevent signal reflections caused by impedance mismatches with input/output devices. This requirement is less critical for analog applications.
Second, look for insulation with a low dielectric constant. The dielectric constant of vacuum and air is close to 1.0, while Teflon (PTFE) is around 2.0. Air-injected Teflon insulation can reduce the effective dielectric constant to around 1.4–1.5. Some products have developed such lower dielectric materials, which can significantly improve signal transmission, especially at high frequencies. Look for cables using such materials.
Once the impedance rating is matched, ideal length that people refer as 1.5-2.0 m can be less restrictive because the reflection is minimized. If cable is high quality, well-shielded and imp. matched, 1 m is just fine and will perform equally well.