Anyone who takes '300' seriously and complains about it being historically incorrect is an idiot, it's based on a comic book which is fictional and fantasy, not everything has to be based on reality, 300 is a good movie and it's entertaining, it's not meant to be historically accurate and educational.
You are right, of course.
I think the OP should edit his first post to create some kind of list, based on the recommendations of this community.
What I would do is to divide the list into sections like "Historically very accurate movies (The Name of the Rose)", "Entertaining with good historical accuracy (Kingdom of Heaven)", "Entertaining with low historical accuracy (King Arthur)" and "Fantasy/Fictional historic movies (300/The last Legion)".
So everyone knows what kind of film it is, because simple attributes like "good" and "bad" don't apply to everyone, because everyone judges things differently. Links to imdb.com would help, too.