Even though Henselt and Foltest are currently on top, the NR card variety isn't that great. All three NR leaders seem to run nearly same card pool (in particular bronze cards) with only other priorities.
The 3 basic Temerian units, 4 siege units(Ballista, Reinforced Trebuchet, Siege Tower, Battering Ram), Reaver Scout, Dun Light Cavalry, Siege Master/Support and for Foltest in particular Aretuzas and Witch Hunter and Ban Aard Tutor.
So with all 3 leaders together the bronze cards that are really used equal only 50% of the factions bronze card pool. While Nilfgaard and Monsters have a similar situation, both get a lot of units, helping to improve the unused cards, while NR hardly got cards that help including the unused ones.
For reverence:
Crach an Craite and King Bran alone use a little less than 50% of the card pool.
The same with Eithne and Brouver, who use together 50% and with Francesca it goes over 75%.
To sum this up, NR is definetly not entirely bad, but there are lot of cards that aren't used that much, but in contrast to other factions there doesn't seem to come much help for them. At the same time, it seems that all 3 leaders are pretty exchangable as they nearly use the same card pool currently.
Also, I honestly doubt, that the Meta will stay this way, as both Foltest and Henselt are not that difficult to counter with the right cards, so the Meta will surely change to counter them.