While they're two very different things with different purposes so i find it hard to compare.
The Musicals start off following the anime, then they decided to make up their own stuff and then start following the manga. Music-wise of course Myu's better with its 100+ songs against PGSM's 19. However, being musicals, they cannot possible characterise everyone properly, they expect the fans to be familiar with the characters already, unless they're specifically focusing on someone. Being live, the musicals have more heart and emotion than PGSM does, however PGSM really is technically better, its got editing processes and the ability to redo scenes. But with Myu its sort of a one-chance thing. I guess it depends on what your comparing. In Myu, you can't just act, you have to really care about your character and everything in PGSM you're able to act out of it, but luckily it seems everyone does genuinely love doing it. PGSM is also quite straightforward but i like how Myu makes you consider the plot more, in particular, Myu uses more thematic devices and subtler techniques to get its point across or convey things, more so than any other version, where they almost always spell it out for you. Myu is just slightly more adult and mature to the other versions, while PGSM is aimed at a young audience, Myu is more aimed towards the parents while they entertain the kiddies with fun and brightness. But again, it all depends on what you're comparing.
For example:
Plot Detail: PGSM > Myu
Deeper Meanings: Myu > PGSM
Mystery and Depth: Myu > PGSM
Characterisation: PGSM > Myu
Singing: Myu > Pgsm
BGM: Myu > PGSM
Predicatbility: Myu > PGSM
Acting: Myu = PGSM
What I love about myu is the perfect mix of professionals and amateurs that make it so heartwarming, everyone comes together in myu to sing and love sailor moon!