I'm afraid I can't offer much about the two Model Shipways Mayflower kits. I know the old one (which, I'm fairly sure, was on the market several years before Mr. Baker designed the Mayflower II) was based on the old R.C. Anderson reconstruction, which, as we established earlier, is an eminently respectable piece of research. I don't know anything about the newer kit beyond what I can see in the photos. I gather it's based, on some level, on the older kit, but it looks considerably taller and skinnier - as though it had been conceived as sort of a compromise between the Anderson and Baker interpretations.
It certainly looks to me like a reasonable reconstruction. Do bear in mind that, when it comes to such questions as whether the capstan was or wasn't under the overhang of the quarterdeck, we're dealing with details that (a) the meager contemporary evidence can't answer definitively, and (b) probably varied from ship to ship in any case. In my opinion any of the kits we've been discussing could form the basis for a credible replica of the Mayflower.
Regarding the other old Revell kits migmodeler mentioned, all I can offer are personal opinions.
H.M.S. Bounty was Revell's second sailing ship kit; it was originally released in 1956, almost simultaneously with the 1/192 Constitution. By 1956 standards it represented the state of the art, and in some ways it can still hold up to comparison with the very best. In many other ways it doesn't come up to modern standards, but it's a basically sound kit. (It was the basis for a model of the ship I built quite a few years ago, as a matter of fact: http://www.hmsvictoryscalemodels.be/JohnTilleyBounty/index.html ). In my opinion it's a better kit than the one that competes with it, which is from Airfix.
The Golden Hind is one of my favorites - an extremely well-detailed, well-designed kit that was originally released in 1965, something of a heyday for Revell sailing ships. If you do a Forum search on the term "Golden Hind" you'll find some interesting discussions about it. Highly recommended.
Revell has issued two kits under the name "Spanish Galleon," neither of them, in my opinion, worth buying. One of them is a slightly modified version of the Golden Hind; that's about as reasonable as slapping red stars on a Sabre jet and calling it a Mig. The other is a much bigger...thing...that was originally released in 1970, when the company was having severe financial problems. I was working in a hobby shop at the time, and I remember some of the literature Revell distributed; it boasted that "we've zeroed in on the market with this one...young married couples and interior decorators." According to Dr. Graham's book, the "research" for this kit was carried out "at the MGM movie studio library." 'Nuff said. I question whether anything that looked remotely like that ever floated.
The Revell "Beagle" is one of the more notorious scams in the history of the plastic kit industry. Originally released in 1961, it's a somewhat modified reissue of the Bounty kit. Those two vessels, in reality, resembled each other only in that each had a hull, a deck, and three masts. (There's considerably less room for argument about this than there is about ships like the Mayflower; good contemporary plans of both the Bounty and the Beagle exist.) In just about any other field of marketing, somebody would have sued the perpetrator of such a stunt for deceptive advertising. My advice to any modeler is to avoid this one at all costs.
Revell has a decidedly mixed reputation among sailing ship modelers. The best Revell kits are among the best ever released. The company has also unleashed some duds on the modeling world - and its habit of re-releasing kits under silly new labels is pretty infamous. (In Revell's defense, more than one other plastic kit company - and more than one of the notorious HECEPOB [that's Hideously Expensive Continental European Plank On Bulkhead] wood kit makers - have done the same sort of thing.) But anybody who's been involved in plastic modeling for any length of time knows that's just as true for the rest of the Revell line - whether you're talking about modern warships, aircraft, armor, cars, or whatever. And much the same can be said about most other kit manufacturers. Caveat emptor. Better yet - make use of this forum before you spend your money.