Imho, I would prefer Nio over Rivian, just its ability to mass produce faster will make it a winner. I don't know whether the cars produced can actually stack up against each other is essential but pricing will negate that factor. Another fact is that Nio have much larger markets to sustain growth and profit. Not saying Rivian can't export but the numbers are insignificant at best in the near future. Another crucial element that is much favorable to Nio is the very fact that China's government huge support and push towards EVs and a smog-free environment. Air Pollution is an extremely delicate and important issue with far reaching complications, impact and consequences to China's well being, economy, productivity, transportatio, and many more. The situation is so bad and increasing in severity that "laws" and "restrictions" are in place to curb the ever raising problem.

Thus, it's impossible to prevent Nio from succeeding unless they have some hidden critical issue from within, 3ven then, the Chinese government might bail them out likt what US did for it's motown industries.