I know a lot of people recommend rules-light games for beginners, but if your group has neither roleplaying experience or theater experience, then something more structured and board-gamey may actually benefit. What I find is that players without any experience fall into choice paralysis in rules light games, and having clearer structures can facilitate learning. It really does depend on what sort of experience your players are interested in. If I had to make a blind recommendation, I think that the Free League "Year Zero Engine" games might be a good candidate if you've never played a TRPG before. They have the right balance of rules complexity for new players, good GM support and high production values. There are plenty of different genres (and degrees of complexity) in the ecosystem.

Some examples that you may want to look at:

• Mutant: Year Zero (post-apocalyptic adventure)
• Dragonbane (fantasy adventure) (Technically not YZE, but it has similar levels of complexity)
• Vaesen (mystery, folklore, horror)
• ALIEN RPG (sci-fi, horror)
• Tales from the Loop (coming of age, sci-fi adventure).

Most of the these games have a starter kit with one-shot adventures that are meant to introduce players to the system and roleplaying more general.