I've never heard the NEC called the best rail in the US. The two NS lines Amtrak uses in Virginia are smooth as glass compared to the NEC. It has an enviable speed rating, but it's not as comfortable as the Dismal Swamp run in Virginia, and I doubt it would be even at 79mph.
I'm thinking the "best rail in the US" to which
Trogdor and
jis are referring is to be understood in the context of contiguous segments linking multiple populated areas, with an FRA track rating of Class-5 or better for use in passenger service.
I used to ride that Great Dismal Swamp stretch of NS many times, when I still worked for both N&W and NS, and yes it historically has been and was well maintained long before the current NE Regionals began to serve the "Southside" of Hampton Roads Va. (South Hampton Roads) starting in late 2012. That stretch was rather "comfy" on the many freights I rode through there ─ whether on one of the company's office cars on ferry between Norfolk and Roanoke or while riding a locomotive cab on my return trip. Of course, those runs were at considerably less speed than 79, and a ride on older 6-axles units like the EMD SD40-2 could make one feel as if he were riding the Tilt-a-Whirl ─ even with that many axles (compared to 4).
But back to the intended point, "gold standard" for the US probably is to be understood as RoW which is maintained for primary use by passenger service operated in (at least) HighER Speed service. Many if not most of us are aware that Amtrak's Illinois and Michigan services include stretches that allow passenger speeds beyond 79, since they have been or are in the process of being upgraded to class-5 track speed. Much of this is shared trackage not owned by Amtrak, although Amtrak does own the 95.6-mile segment of track between Porter, IN and Kalamazoo. But the same can be said about lot of track in the West, maintained by BNSF to class-5. A ride west of Albuquerque on the "SW Chief" demonstrates how fast those big rocks zip past those Superliner windows at 90 MPH, because the BNSF has the signal equipment necessary to operate its own trains allowed by that track class. But in the case of freights, speed not only is limited by track class, but also by the engineering dynamics of the rolling stock, as well as with the gearing constraints of high-horsepower locomotives (AC4400s, SD70/90s, GEVOs [GE Evolution Series], etc.).
Finally, "gold standard" contextually implies priority scheduling for passenger-train service, generally only possible within the NEC and with existing portions of Brightline. The STB very recently approved Brightline West's request for authorization to modify portions of a previously authorized alignment, and this allows relocating the rail alignment on certain portions of the Line from the east side of the I-15 freeway to its median. Brightline West very well would augment what can be referred to as "gold standard" in the US, to incorporate the new dedicated Cocoa-to-Orlando (MCO) and the proposed extension MCO-to Tampa. Although diesel-electric as opposed to external-electric with the NEC, Brightline higher speed service appears predicated on a business model of higher-speed operation wherever possible and practical, discounting the shared segment between Miami and West Palm Beach (limited to 79 MPH).
Again, it's all relative to what North America already has had during the last 7 decades.