[Zababa]

As a French, the Amerian accent is usually the easiest to understand. That's also what most people around me think, though they also think of the British accent as more "fancy". This is for the "American you hear on TV" accent. which is also the one that I hear the most on Youtube or sites like that.

You're right about clarity not being a function of accent, at least not totally. There are some people that speak terrible English with a French accent, and others that speak clear and easy to understand English with a French accent. The same applies to pretty much every accent. I also agree with you on the soft power, however part of the soft power will mean that people are more used to the NA accent.

As a final point, I've heard multiple times that sometimes people that speak English as a second language can understand each other really well while Americans have a really hard time understanding them. If that's a real phenomenon, then having a non-American accent could be detrimental if you want to work in the USA.