It depends upon what's failed, and where I'm going.
20 miles with flaps stuck down, I'd land at whichever had the best maintenance facilities. Flaps stuck up? - I'd do the flight in most cases, but certainly favour landing where I could get maintenance support.
Radio failure? Depends where I'm flying (through and to), but I'd not cancel many intra-national flights for a radio failure. International I have done, and would do again.
Primary controls (aileron, rudder, elevator), any restriction I'm landing as soon as possible.
Trimmer? Depends what trimmed and how badly / in what position it failed.
Doors and windows? Depends?
G