Like any stamp, I am looking for decent centering, no pulled perfs or any other faults.
After that is settled, then there is the matter of the best possible cancel. Here's my cancel criteria in order of most preference to least preference.
CDS (preferebly SON)

Partial CDS

A nicely placed Slogan Cancel

Light cancel

Cancel covering smallest area of stamp

Valid Postal cancel of any kind (when no other example is available)

A page from my album:
