I want to recommend that you play the latest remake in the series, Lunar: Silver Star Harmony on PSP.

The only issue with that recommendation is if you plan to play both games in the series. Lunar: Eternal Blue, the sequel, is only available in English on Sega CD or Playstation, so you should choose one of those if you plan to play it.

The old Sega CD versions are my favorites because of my own nostalgia and childhood with the series. They are markedly dated games, and the game mechanics are a little hard to understand. Lunar: The Silver Star, for example, has no elements in its magic system, and Lunar: Eternal Blue made you pay to save your game.