Great suggestions, every single one. Instead of just adding more names to the list, I can offer an observation... based on my snobbish opinion, but an observation, none-the-less... *Let's avoid pipe tobacco Political Correctness for a minute and just straight talk this for a minute...
American; McClelland has a ketchup-y aroma in the tin, but the flavors of the smoke is outstanding, ranging from sweet to full bodied, chocolate-y notes. No, it doesn't taste like chocolate, just has that cocoa-ness to it in some blends, as well as some may be more lemony acidic, or even have a natural subtle spiceyness.
Most C&D Virginias, used alone and in their blends, look, smell, and taste air cured. It is more scorchy on the tongue, but many pipe smokers still like the flavors. To me they lack a depth and I can tell that there is sweetness in there, but it just doesn't seem resolved. Thus, the air dried conclusion, like raw corn is not nearly as sweet as cooked corn. ...if that makes sense. I put D&R and GLP in this category also, however, I think GLP may be using some better Virginias in some of his blends. And, just becauise I think most of these are more raw tasting, doesn't mean that they're bad, just more... raw tasting, ha ha.
H&H has a variety of Virginias, some similar to McClelland and some more similar to C&D. I assume that H&H isn't processing their own Virginias. Maybe they are a large enough operation, IDK. But, they have some unique flavors in some of their blends, but some still seem more McClelland-y or more C&D-y to me. This was not said out of any knowledge of how H&H works, just from having sampled their selections, which of course by the suggestions above they have some good stuff.
European; I find that most European Virginias aren't in the same ballpark as C&D and McClellands. Most all seem to rely on the subtle casing flavors like licorice, honey, or other sweeteners and processes like pressure and such. Meaning they are more heavy handed with the flavors in the casings and rely on making flakes to offset some of the issues that a smoker might have with raw flavors and biteyness.
MacBarons, Pure Virginia is the only Virginia by them that I would suggest to a friend. Virginia #1 is what I suggest to enemies and evil tyrants, because it is so artificially sweet that it is bitey as a mouthful of rattlesnakes. Everything else in their lineup is too aromatic for me.
Peter Stokkebye has one very unique Virginia, and that is Luxury Twist Flake. It is a Virginia Cavendish, and while I tend to run from flavored tobacco, this one is interesting enough that I smoke it mixed with VaPers very often. Their Luxury Navy Flake is good, but to me the Virginia in the mix is like an air cured that was pressed. It has lost a lot of that stringent-ness in the process, and it's not terrible.
As far as European Virginias go, there are a few others that lack the added flavors, SG FVF, Best Brown, a couple of those Seasonal releases, I can't remember which season was what, but... GH&co, Curley Cut Delux stands out. I haven't found anything else from them that comes close to an American Virginia. Homberger Veermeister and Limerick are pretty good. Then there's staples like Escudo and such. There are a few diamonds hidden the haystacks of European Virginias, but the best of European Virginias just come close to what is produced in the US. Worth exploring, but be cautious.
When you get a palate vocabulary built up for the subtleness of Virginias, explore McClellands more in depth, the Blackeny process, stoved, matured, etc... Sundowner, Aurora, there really is a vast range of blends and single leaf that can give you a huge variation of flavors that are naturally coaxed from their offerings. If I could wear a patch that endorses any one tobacco company it would be a big, proud McClelland patch. In tinkering around with growing and processing my own Virginias, I am most enamored by what they do, and that fermented Virginia aroma that you'll get from their produce.
*Note, that I use words like most and some and genralities, and I avoid painting these companies with absolutes. So, before someone gets their panties in a wad, this is just my observations. If everything gets nitpicked, it just makes it harder to talk about tobaccos or really anything. Let's avoid pipe tobacco Political Correctness. It's just my opinions, and I am only an expert in those opinions. YMMV