I wouldn't want to pronounce any model manufacturer categorically "better" than another. In evaluating a kit, all sorts of things need to be taken into consideration: its accuracy, its age (it's not reasonable to expect a 1956 kit to be comparable to a 1995 one), and - as scottrc quite reasonably points out - what you intend to do with it.
The first Revell sailing ship kits (Constitution, Santa Maria, Bounty) were state-of-the-art in the 1950s. They don't come up to today's standards - as the airplane and car kits of that era don't. In the intervening period (almost fifty years now) just about every model manufacturer has produced kits of varying quality. Some of the Heller kits (e.g., the one they call "La Sirene," and the "Reine Mathilda" we discussed in this forum a few weeks ago) are ornamental caricatures rather than scale models. The best Heller produces (H.M.S. Victory and galley La Reale, for example) are, in my opinion, among the finest plastic kits ever produced. Same goes for Revell. I'm a big fan of their 1/96 Constitution, which, in my opinion, can compete on pretty equal terms with any wood kit I've seen. (Caveat: I certainly don't claim to have seen them all.) Their little Golden Hind and Mayflower kits are really nice, as is their Charles W. Morgan. They've also produced some items that, in terms of scale modeling, can most gently be described as junk. (Granted - they may make nice decorations, and give some people a great deal of satisfaction. I'm talking strictly in the context of scale modeling. That "Spanish Galleon" isn't a scale model.)
The best Revell kits are far more accurate than the worst Heller kits - and vice versa. (I haven't seen any of the new Trumpeter ones - other than the big aircraft carriers, which look pretty good.) Similarly, I'm sure aircraft modelers would agree that the best Revell kits are more accurate than the worst Tamiya or Hasegawa kits. The unfortunate truth is that the buyer needs to beware. That maxim applies to all forms of model building; unfortunately it's especially true in the area of sailing ships.
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.