Lua's feature set is tiny, and that's precisely what I love about it. Ruby feels a lot like Lua, but I vastly prefer Lua to even Ruby, because of how minimal it is. As someone who writes ES6 on a daily basis, I feel that Lua's syntax explains itself -- you can start writing Lua code in 30 minutes. People have always said that Python is fun to write, but I've never felt that about Python. On the other hand, I can definitely say that Lua is pleasing to write in. Python, to me, has always felt like a chore compared to Lua.
Funny, it's Lua that feels like a chore to me, because most things take around twice as many lines of code than in Python. (Though some of those lines are just 'end'.) I want to like Lua more because it's so much simpler and faster, but it could've come closer in expressiveness and catching errors.
I'm on the python side of the fence, even though it's not my favorite thing by far, I rapidly clicked to their idioms. I like lua for all the reasons people say lua is great but I always forget it :)