PS1 by a mile. Every other version has either worse graphics, removed cutscenes and/or fucks up the music score (including the GoG version, unfortunately). The soundtrack plays a BIG part in making the first Rayman so good, so playing a port with a worse soundtrack is not worth it, imo.

Even better, Rayman Redemption is a free fangame that contains all the content from the best Rayman, and expands upon it. I'd say it's the best way to experience this classic.

EDIT: Although I wholeheartedly recommend Rayman Redemption, it would be a bit irresponsible from me not to mention that it is a fundamentally different game compared to the original: a non-exhaustive list of changes:

• All power-ups are unlocked from the start (which makes for a less slogg-y beginning, but does make the first few levels a tad bit easier)
• Most levels have been expanded, either with longer screens or entirely new levels, boss battles and collectibles.
• An overall less grindy experience (more lives, being able to unlock additional hit points and gloves power-ups).
• Different physics (such as: being able to hit small enemies more easily; helicopter-hair being more similar to how they work in the sequel games; Rayman now stays in place when he is hit instead of jumping backwards, which makes the eggplant-riding challenges a LOT easier).
• Some QoL features, such as keyboard/controller setup, options for resolution and aspect ratio, gloves power ups being visible on Rayman's sprite, full-charged glove having a different loop animation from the normal throw animation, etc...

TL;DR: If you want to experience the original game as it was intended, PS1 is the best port to experience it. If you want a more modernized experience, Redemption is the way to go.

The MS-DOS version of Rayman was the best one. All of the console versions had to cut various things from it. Lower resolution sprites, removing layers from the soundtrack, etc. The Sega Saturn was probably the closest to the MS-DOS version, and that one isn't included in this edition.

I'm not really sure if this new $20 edition is worth it. You can get the MS-DOS version, plus the bonus levels mentioned in the blog post, for $1.50 right now. https://www.gog.com/en/game/rayman_forever