First, welcome to the Forum! You'll find that this part of it, at any rate, is inhabited by some rather odd people, but most of us mean well and are, in general, harmless.
Maybe a good way to start an answer to this question would be to clarify the terminology. Unfortunately, when we're talking about sixteenth- and seventeenth-century ships, that isn't always easy. That word "galleon" seems to have been kicked around so much, and so casually, over the years that it has scarcely any specific meaning. For what it's worth, here's the definition from the glossary of the relevant volume from the "Conway's History of the Ship" volume, "Cogs, Caravels, and Galleons: The Sailing Ship, 1000-1650." (Please excuse the quotation marks instead of italics. My computer seems to have lost the ability to include italics in this Forum.)
"Galleon. Sea-going full rigged ship of the sixteenth century and later, characterised by a relatively high length-to-breadth ratio, a long beak under the bowsprit and a crescent profile rising somewhat higher at the stern than at the forecastle. COmpared with carracks (qv), the lines of the galleon were finer, the superstructures lower, and unders sail both speed and handling were superior. Galleons were usually heavily armed, although they were not necessarily specialist warships. The term came to be closely associated with the Iberian powers, and in particular Spain, so that by the seventeenth century almost any large Spanish ship could be described as a galleon."
The only English ship mentioned by woodburner that really fits that definition is the Revenge. The old Airfix kit isn't a bad one - especially in view of its age. It doesn't have a great deal of detail. The lower deck guns, like those in all other Airfix sailing warships, are "dummies" that plug into holes in the sides, there's no detail on the insides of the bulwarks, and the deck furniture and spars are pretty rudimentary. But the basic shapes are entirely believable; the material is there to form the basis of a fine scale model.
The Golden Hind and Mayflower probably were too small to meet the definition of the word "galleon," but they're well-represented by plastic kits. Both the Revell Mayflower kits, in my opinion, are among the best dozen or so plastic sailing ship kits ever produced. The Revell Golden Hind doesn't have quite the level of refinement, but it's an excellent kit - one of my favorites. The Airfix Mayflower isn't a bad kit by any means. It's not based on the William Baker Mayflower II plans (like the Revell ones are); I'm not sure what the basis of it is, but it looks pretty believable to me.
I know the Airfix Golden Hind and the various Imai kits only through pictures. My general impression is that the Airfix Golden Hind is a basically sound kit, but somewhat simplified. Our resident Forum expert on the Imai line, Millard, will I'm sure have some things to say about the Imai (aka Ertl) Golden Hind. (Later edit: I see Millard and I were typing our posts at the same time.) I have the impression that the Trumpeter sailing ship kits are reissues of somebody else's, but I'm not sure whose. They seem to have the reputation of being quite simple and basic - but that doesn't necessarily mean there's anything wrong with them.
I'm not aware of any definitive date for the initial appearance of the open stern gallery. It appears in at least one of the drawings in the so-called Matthew Baker Manuscripts, which apparently date from about the time of the Spanish Armada and are generally regarded as the earliest genuine English ship plans. I suspect the presence of such a feature did indeed imply a certain "classiness," but I don't have any definitive evidence to back that up. (It's perhaps worth noting that when Brian Lavery, one of the best in the business, designed the replica of the Susan Constant that's now at Jamestown, he gave her a stern gallery. She's a small-to-medium-sized merchantman. But William Baker didn't put a stern gallery on the Mayflower II.)
As for the relative accuracy of all those kits - nobody really knows for sure. The source material about this period in the history of naval technology is so sketchy that it really would be unfair to condemn any of them. (It's possible for a plastic kit manufacturer to go so far offbase in designing an early sailing ship that the result simply isn't believable. Heller used to do that on a fairly regular basis. But the kits we've been talking about here aren't in that category.) I feel comfortably speaking up on behalf of the Revell Golden Hind, the Revell Mayflowers, and the Airfix Mayflower and Revenge. I haven't seen enough of the others to form opinions of them.
The sad part of this discussion is that every one of the kits we've been talking about is, so far as I know, currently unavailable. Swap meets and e-bay probably are about the only places to find them - unless one has the good fortune to have a Forum friend like Big Jake, who supplied me with my Revell Golden Hind. The plastic kit companies have almost abandoned the sailing ship concept. At this point I've just about given up any hope of any good, brand new plastic sailing ship kits. But if some of the grand old kits from previous generations would reappear I'd be happy.
Hope that helps at least a little bit. Good luck.