The Fuma Conspiracy. Happened to get lucky, though my copy used to belong to a library before they sold it for cheap. They had no idea what they had. It's the Discotek version.
It was a great film, with great animation, and Murasaki was a wonderful character. Wish she appeared in more. It was also nice to have a decent focus on Goemon, since we don't get that too often. Plus, it's always awesome seeing Lupin and the gang go on heists, and this film is home to one of the franchise's best car chase scenes.
The English dubbing was...amusing. Lup...I mean, Rupan sounds like a dork, Jigen sounds a bit stoned, Fujiko, I don't know what to make of, and Zenigata is perfect.
If there's one thing preventing me from fully reccomending it, it's the freaking price. It may be gold, but it's not so good to be worth over $100 for the Discotek version, and I might have gotten the older AnimEigo DVD had the library copy not been put up, and even the older release seems to go for $50-60, going by Amazon. No offense, Reed, but I don't think the extra features are worth $100.
So while it's an amazing film, if you're just getting started with the franchise, the price alone is reason enough for me to say "don't start with it" unless you can borrow a friend's copy, and once you decided you like the franchise, I say go for it, but AnimEigo's older release may be the better value due to being cheaper, though still by no means cheap.