Reliability – does it consistently do the job it’s required to do?
Durability – is it likely to last a long time?
Appearance – is it easily identifiable?
Brand – is it from a reputable manufacturer?
Shear strength – is it resilient while twisting?
Compatability – does it match the lock?
Turnability – is it easily turned or does it sort of stick and require wiggling about?
Master – all hail the master key