I don't know of a straight virginia with a high nic hit other than Royal Yacht, which is currently out of production.
Of the straight virginias in my rotation, I guess FVF has the most nicotine and I would rate it at about medium.
Edit: I tried a small sample of Bad Nun once. It is a straight virginia with a lot of nicotine, maybe up there with Royal Yacht and Irish Flake. I liked it very much, but it is difficult for me to get my hands on. It is distributed by Synjeco and produced, I think, by Gawith & Hoggarth.
If you are looking for an American straight Virginia with a little more stregnth than FVF, try some of Daughters Ryan’s Virginias, maybe Three Sails or Windsail Or, C&D has a Virginia Flake in bulk that tops the medium catagory in bulks. Their Briar Fox is also a smidge stronger, but it has burley blended in for a balanced flavor.
You’ll have to turn to ropes for stronger, but those Empire Virginia won’t have a traditional Virginia flavor like you may be thinking of.
1 one for Cosmic,Yes those so-called Empire Virginas differ quite a much from Regular bright Virginias,that's for sure, moreover I happen to have soft spot' for majority of British Otc blends which tend to be Virgina forwards, and all these are far from being light in taste nor they are bright in color,as I understand many of them do have some dark fired Kentucky leaf as condiment.
G&H ropes, Brown Twist Sliced if you don't like preparing ropes. Get a good fish filleting knife if you've not tried it, you can slice consistent 1/16" coins out of ropes and rub them out. Their flavored ropes are mildly seasoned, so the Rum or Maple varieties would probably be considered lightly flavored. (I would say very lightly). Brown Irish X might be a good choice for no flavor added.
C&D Small Batch Carolina Red Flake, unfortunately, they produced 8,000 tins a few weeks back and it lasted less than 24 hours online. Anyway, keep your eyes open for it next time. Some say the nic content is moderate, to me it's more than just moderate. It's pretty much straight out of the fields, so it's got some bite and probably could use some ageing...anyway, keep your eyes out for it next time.