I really like the NQ climb, but I feel like the GSM route has created more nice accessible loop options on Seymour. I was riding almost exclusively Fromme for a while, but GSM might have tilted my preferences to Seymour. GSM makes that whole west side of Seymour really loopable now - two or three laps up GSM, maybe a John Deere miniloop (or whatever it is) and you can get some really mixed and varied riding in a solid couple of hours.
NQ is definitely being filled in, more little bits added here and there but, like most it seems, the only part I don't like is the skid road ascent - it's just hard to get a rhythm going. And it is a bit of a lung-buster. I like linking a couple of climbs using NQ - park near Dempsey/Braemar and take NQ up to Mtn Highway, 7th/Crinkum/Kirkford descent, maybe a small Floppy Bunny or Bobsled loop, climb back up and take any of the trails down to Pennzoil and back to the car. That ends up being about 15km and probably 800m - that's a pretty decent ride.
I'll often decide my route based on whether the parking lot on Fromme is full - if it is, then it's either No Quarter or that climb up the King of the Shore and stuff that others have mentioned.