In any serious discussion of this topic it's a good idea to start out by understanding just what these various kits are.
The old Aurora one (copied by Smer) is a product of the early 1950s. It represents a popular, Americanized conception of a Viking ship: dragon's head and tail on the bow and stern, striped sail, brightly-decorated shields along the gunwales, and a crew wearing horned helmets. I, like lots of modelers from my generation, have a warm spot in my heart for it; it was great fun for a kid getting interested in maritime history to build, and a big factor, I'm sure, in getting lots of people into ship modeling. But it isn't a scale model of anything. There's nothing Norse about the shape of the hull, the deck arrangement (such as it is) doesn't match any of the archaeological evidence, the charactersitically "clinker" hull construction is conspicuous by its absence, and the decorations are vintage 1950s American. (Though I haven't had that kit in front of me for at least thirty years, I can still close my eyes and visualize that dragon head in all its wonderful detail. But imagine what it would look like full-size. And think how much the piece of wood from which it was carved would weigh.)
Two major Norse vessels, and quite a few fragments of smaller ones, survive. The two biggest ones (both of which have been the basis of plastic and wood kits) are in the Viking Ship Museum in Oslo: the Oseberg Ship and the Gokstad Ship. (The names "Oseberg" and "Gokstad" had nothing to do with the ships originally; they're the names of the farms on which the ships were found.)
The Oseberg Ship is a relatively small, highly ornate vessel with low gunwales. It was found in the burial mound of a woman (perhaps a queen or a chieftain's wife). Scholars are pretty much agreed that it was built as a ceremonial barge - not a seagoing ship of any sort. Relatively recent research, including dendrochronological study on the wood, has established that it was built in about 800 A.D. and interred in about 834.
Heller issued a kit labeled "Drakkar Oseberg" back in the early seventies. (The label should have tipped me off right away that something was wrong. "Drakkar" was a Norse term for a "longship," a big, seagoing, semi-military vessel. The Oseberg Ship most definitely is not a drakkar.) Apparently the people who designed the kit didn't bother to look at the real vessel, or a set of plans for it - or even any decent photographs of it. The kit's hull is distorted in proportion to the point of caricature, and the "carved" details (normally Heller's strong suit) bear no resemblance to those of the actual ship. That approach is pretty hard to excuse. Good, detailed plans of the Oseberg Ship are easy to find - and have been for decades. The standard book on the subject, The Viking Ships: Their Ancestry and Evolution, by A.W. Brogger and Haaakon Shetelig, has been around (at least in its English-language edition) since 1951; it contains excellent, easily-understood plans for both the Oseberg and Gokstad Ships.
The other big, famous ship find is the Gokstad Ship. This one is considerably bigger and less ornate. The researchers have established pretty firmly that it was built in about 890 A.D. and buried about twenty years later. (The hull planking has been damaged and repaired at several points; scholars are pretty much agreed that this vessel saw considerable active service before being interred.) The Gokstad Ship is a remarkably well-constructed vessel, clearly intended for long voyages over open water. It probably was built as a general-purpose ship, for both militant and peaceful purposes. The Norse probably didn't make a rigid distinction between "warships" and "merchant ships." Whether this one was ever used for terrorizing English or French villages, or for hauling cargo, or for carrying people back and forth around the fjords, is anybody's guess; there's just no evidence. But it was a genuine working ship of some sort.
A full-size replica of the Gokstad Ship was built and sailed across the Atlantic in 1893, in conjunction with the Chicago World's Fair. (The idea apparently was to draw attention to the achievements of Leif Ericsson, at a time when Christopher Columbus was getting lots of publicity. It's since been established that Leif's ships didn't look much like the Gokstad Ship - but hey, what the heck.) The captain and crew of the replica reported that it handled beautifully during the crossing; the hull structure flexed as much as six inches without leaking. The replica eventually ended up in Grant Park, near Chicago. I'm not quite sure what its status is today; as of a few years ago a local group was raising money to do a major restoration job on it. (Maybe a Forum member from the Chicago neighborhood can fill us in.)
According to Dr. Graham's history of Revell, the Revell kit is based on the "Grant Park Viking Ship." If so, the people responsible for building the latter, in 1893, must have been extraordinarily precise in reproducing virtually every feature of the Gokstad Ship. The Revell kit is simplified a little in a few places, but in its overall shape and details it matches the plans of the Gokstad Ship in the Brogger and Settelig book exactly - down to the apparently rather arbitrary layout of the deck planks and the inconsistent width of the hull planks at the bow and stern. (The biggest deviation from the plans is one I don't understand: the kit's "main deck" - if we can call it that - extends aft, under the little "afterdeck," by several feet more than the real thing does. The real deck terminates at the last thwartships beam. The extra length would be almost impossible to see on the finished model. Maybe it matches the Grant Park replica?) I'll say it again: in my opinion this is one of the finest plastic sailing ship kits ever released.
The Gokstad Ship was buried with sixty-four wood-and-metal shields, painted alternately black and yellow (no designs on them), which apparently were hung on the ship's gunwales. It's pretty generally agreed that shields were hung on the sides of Viking ships for ceremonial purposes (perhaps when the ships were entering or leaving port, or on other special occasions). They wouldn't have lasted long in a seaway, and wouldn't actually have been of much use in a fight. The Revell instructions, interestingly, suggest the option of omitting half of them.
Revell's renditions of the Gokstad Ship's shields are excellent, but there's a small glitch in the painting instructions that might mislead the unwary. Each shield consists of several wood boards, with a dish-shaped boss in the middle and a rim around the edge. Revell suggests painting the shields as though both the central boss and the rim were iron. Not so. The central boss is iron all right, but the rim is leather, held in place with lots of little iron nails. If the rim were in fact iron the shield would be mighty heavy.
I haven't seen the Emhar kit, but it seems to be the only one on the market that's actually advertised for what it is: a scale model of the Gokstad Ship. On the basis of the photos that have been posted on the web it appears to be a fine kit; as I mentioned in an earlier post, in some ways it beats the Revell one. I started my Revell version before the Emhar one was released. If I were doing it again now I'd have trouble choosing between them.
In other words, either the Revell or Emhar kit has the potential to produce a first-rate scale model of the Gokstad Ship. Turning the Heller kit into a scale model of the Oseberg Ship would be just about as difficult as starting from scratch. (The various modified versions Heller released later are, in terms of historical fidelity, even worse.) And the Aurora/Smer version is great fun, but not, by most reasonable definitions, a scale model.
Viking ships make beautiful, challenging model subjects. Even if one starts with the intention of making a scale model of the Gokstad Ship, there's plenty of room for interpretation - and plenty of necessity for guesswork. The real ship was buried in such a way that the stem and stern projected upward into a more acidic layer of soil; they've rotted away just a few feet above the gunwales. Whether they ever had any sort of decoration on them is anybody's guess. (The only purely ornamental work on the Gokstad Ship is a bit of carving on the tiller, and a series of simple beads along the edges of the hull planks. Revell, unfortunately, didn't reproduce the beads - and I confess I didn't either.) The mast was hacked off a few feet above the deck, to form the centerpost of the structure in which the body of the chieftain (or whatever he was) lay; nobody knows how tall the mast was originally. And, apart from some interesting blocks and some bits of rope attached to them, there's no evidence whatsoever of how the ship was rigged. Plenty of room for the individual modeler to come up with his/her own solutions.
I haven't yet bumped into any pictures of finished models based on the Emhar kit. I suspect that, especially with the addition of the figures that Emhar also sells, the results could be pretty spectacular.
One other thought. Anybody wanting a smaller Viking ship model would be well advised to look out for the one produced by Imai, during that company's brief heyday in the late 1970s. Like all other Imai ship kits, that one was definitely worth building. As I remember, it was six or eight inches long. It shows up occasionally on E-bay.