Tbh if most of the time that you talk to people they either know exactly the plausablity of what Musk is saying or they just read a headline. Most of the time it is the later but there are a lot of advocates in the former that call him out on his plans.
In my groups it's def Musk, however I can see how Bezos would do well with a business crowd since he started on Wall Street (although, not like they did).
Businessman? Bezos for sure. He's the Sam Walton of our generation.
Inventor/technologist? Musk. I'd guess that most people would believe Musk if he said he was going to start building a car that ran on water.