All your sentences are grammatically correct.
I'd prefer "más me vale que" for a situation in which you are evidently threatened or there is an obvious consequence if you don't do otherwise. Maybe you're seeing the other person getting uncomfortable talking to you, or a boss approaching to scold you for not working.
Some examples:
- Más te vale que la casa esté limpia cuando llegue. -> You'll face consequences if the house is still dirty when I'm back home.
- Más le vale al gobernador cumplir sus promesas. -> The people will react if the governor doesn't keep his promises.
- Más me vale salir corriendo. -> Something bad will happen to me if I don't rush out now.
A more common way to say it: "Bueno, mejor te dejo seguir trabajando".
