I've yet to see a really good movie version since the Flynns (which are full of historical anachronisms as well, but just have such a charming cast and a delightful swashbuckling feel that it's quite enjoyable), but if you're willing to include TV adaptations, the 1980s UK production "Robin of Sherwood" is a cult classic with good reason. It's uneven at points and ends rather abruptly with plot threads hanging, but it's got some fine actors, a lovely Clannad soundtrack, and introduced a lot of elements that have been a lingering influence on other series and films since it first aired. While there are some individual weak episodes (and occasional iffy bits in otherwise better episodes), the series as a whole is really pretty decent.