LOL here we go. The answer is actually “none of them”. This is why I have a GPSDO and that’s not even the truth but a well formed opinion.
The actual truth is too complicated for our primitive instrumentation.
Notice I said that the 7260A was "most likely" the most accurate. For my purpose it will be my "standard"
As of right now I have no intention of going any further with this time nut stuff. It makes my head hurt.
geeeeeze med......yer killin' me!
have you been pickin' your feet in Poughkeepsie?
if you own more than 2 counters are you ARE a time nut. but the .5ppm xtal in that 7260a is not gonna cut it. (250 Hz off at 500 Mhz is crap)
not that i am an enabler.....but if you had a decent ocxo like this one you would be confident of only being 5 Hz off at 500 Mhz. (sure...ya' gotta' let it warm up for an hour to get to 1 part in 10^8).
in the pic the 5335a is referenced from a rubidium that measured -1.5 x 10^-11 when compared to the gps standard.
the ocxo occasionally bounced to 10,000,000.01
go ahead....dare me to put that ocxo in a usps box.