For experiencing Morrowind in its original form, I would definitely say OpenMW is the best way to do that. It works well on modern operating systems, allows playing in higher resolutions and has some quality of life improvements, like greater rendering distance and practically no loading times.
Some folks prefer to mod it, and I'm not really up-to-date on that, but I assume there's still more mods out there, which target the original engine...
Omg, this is huge! The "Voices of Vvardenfell" and "Tamriel Rebuilt Voices" projects are morally questionable as they use AI generated voices trained on the very little voice acting in morrowind without permission from the actors, but it certainly does bring a lot of life to a 22 year old game like Morrowind. And with 0.49 it'll finally be possible with the proper Lua scripting support, which is great for non-windows gamers.
I feel like this is the kind if fringe example where ai is fine. This game is old enough to smoke, it's original actors aren't coming back to it, and no one of profiting off an open source moded engine to make the game run.
It's a fringe example where it's legally okay as the Construction Set EULA that you have to agree to to use the original engine's modding tools grants you the right to make derivative works of the game's assets (including the sound files) provided it's only to make mods for Morrowind (and some other restrictions, e.g. not charging any money). For nearly any other game, no one's granted you that right, so it's not legal, but any other kind of modding that requires you to make things based off the game's original files and distribute them wouldn't be legal either.
Morally, it's dicey as a modern voice actor contract would either have a clause about being unable to use the recordings to train voice synthesis, or charge more for the privilege, so the voice actors for Morrowind signed a right away that they didn't intend to because their agents failed to realise it was something they could do or predict that it would ever become relevant. No one tricked anyone, but it's not what would have been agreed to if everyone involved was clairvoyant.
You have made a mistake and in doing so summoned an OpenMW developer to this thread. Lua is not an acronym, it's Portuguese for moon, so should not be written in ALL CAPS.