May I be forgiven for jumping in here? (If not - well, one of the great things about this Forum is that you can quit reading at any time!)
In talking about the relative quality of model companies, we always need to remember that most of them have been around for a long time, and the quality of their kits has changed over the decades (generally, but with plenty of exceptions, for the better). Airfix has been in business since the early fifties, and Heller for almost as long. If I'm not mistaken, the first Airfix sailing ship was the Endeavour, and it was, by modern standards, extremely basic. As Airfix sailing ships got newer, they got better. The Prince is certainly better detailed than the Victory, which is better detailed than the Sovereign of the Seas. And the Airfix Wasa and St. Louis can stand comparison with anything on the market.
I'm also a fan of the Airfix Cutty Sark - one of the few kits in the sailing ship line that are still available. In some ways it's better detailed than the big Revell one. I also like the Airfix Revenge and Mayflower. I haven't seen the Golden Hind, but on the basis of photos it looks like a nice kit.
Airfix sailing warship kits do have one feature I really dislike: those "dummy" gun barrels that plug into holes in shallow depressions representing the gunports. To be fair, the depressions got deeper over the years; those of the Wasa are much better than those of the Victory.
Airfix did have one dud (in my opinion): its HMS Bounty. That one appeared in about 1980, when Airfix was having major financial problems, and is riddled with silly mistakes (like a maindeck that's mounted on a pronounced slope, because the hawseholes are in the wrong places). Anybody wanting to do a Bounty in plastic would be far better advised to pick the old Revell kit.
The Airfix line had/has several big general virtues. All the kits (the Bounty excepted) are the right shape, and the details that are there are right. I get the impression that the designers were doing the best they could to produce historically accurate models, given the limitations of technology and budget. And Airfix never released a sailing ship kit under more than one name.
I've vented about Heller already in this thread, so I won't bother doing it again.
Bottom line: if you're most interested in "carved" ornamentation and lots of parts, you'll be happy with Heller (though the more recent Airfix kits can certainly compete). If you care about historical accuracy, you're (almost) always safe with Airfix - and rarely, but occasionally, safe with Heller.