As far as I'm concerned the only Three Musketeers movie worth watching is the Disney one with Oliver Platt, Keifer Sutherland, Charlie Sheen and Chris O'Donnell. (Historically accurate or not, it's terribly entertaining!!)
Hallmark Channel did a re-imagining/sequel called La Femme Musketeer, with Michael York as D'artagnan, and John Rhys-Davies as Porthos. The sons of the three are Musketeers (and a lot like their fathers), and Valentine D'artagnan wants to join. They quickly get involved in a conspiracy by Cardinal Mazarin to keep France and Spain at war by kidnapping the Spanish princess. Not as good as the Disney version but fun.
Which is the big key to the Disney version. It doesn't follow the book much at all. And yet, it has the spirit of Dumas' book. The characters - except for Rochefort, and Buckingham - are pretty much spot on. And Tim Curry just chews that scenery. They had to film on location, because he would have eaten every set they had otherwise.
I also recommend the BBC(A) series. Will be shocking in a couple weeks to watch Richelieu on this, and then Doctor Who. (Much like watching the movie Doctor Who and the Daleks, then Star Wars). (Peter Capaldi is the Cardinal). Doesn't much follow the book, but has the characters (Athos, Porthos, Aramis, D'artagnan, Treville, Richelieu, Milady, Constance, and the royals) accurate. I hope they will introduce the valets eventually.
Speaking of the valets - yet another example of how close and so far the steampunk version was. It is the first version I've seen, to have any of them. And they cast Jon Snow's buddy - so the Musketeers could have someone to literally excrete on. A classless act that doesn't fit any of the Musketeers.
Someday, I hope to get a chance to see some of the earlier versions. I've heard there were some very exceptional ones. I believe the Oliver Reed ones DaveMac mentions are the ones in question, as they also have Michael York.