Just started watching 7th Voyage of Sinbad, and I have to say, this is one of my favorite Harryhausen movies! Kerwin Matthews is a good Sinbad, so is Kathryn Grant as Parisa. Koura is cool, but I definitely say the show stealers are the monsters themselves, the two-headed Roc, the snake woman who can still scare people, the Cyclops, the Skeleton, and the Dragon. The fight between the Dragon and the Cyclops is still cool to watch, but the Skeleton fight is expertly and seamlessly choreographed.
Jason and the Argonauts, it's easy to see why Harryhausen himself admires this as his best work, though he was most proud of his Medusa in Clash of the Titans. As a bonus in Mysterious Island, the Nautilus you see is the same one from 20,000 Leagues under the Sea by Disney! Herbert Lom is Captain Nemo instead of James Mason though. Oh well, can't have everything.
Side Note: Daniel Radcliffe (Harry Potter) placed Jason and the Argonauts as one of his favorite movies!