English Electric Canberra
Hawker Hunter
Douglas A-4 Skyhawk
MiG-21
Dassault Mirage
MacDonnell F-4 Phantom II
Nothing else yet meets the Criteria:
Seleted by a least a dozen airforces, still in frontline use in most of them 20 years after first flight, considered worthy of major modernization by at least one "advance technology" air force at 25, still front line somewhere at 30, still in use somewhere at 40.
One final characteristic: 5 of the 6 survived their parent manufacturer by decades.
That one was in service with the USMC for over 30 years if I recall correctly, if not, for a good long time.
If longevity is the criteria and front-line service not just "somewhere" but right here in the USAF, then the B-52 wins AGAIN. It is considered so valuable and dangerous that unlike all the those in your list, it has never been sold to a foreign country.
The first one entered service in 1954 so this year is its Golden Anniversary.
Runner-up, the C-130. Although it has one significant edge on the B-52 in that, last I checked, they were still making 'em.