Pretty much all the evidence is that the "Servant Leader" who has some humility outperforms the "big ego" leader in every way.
Unfortunately the Narcissistic personality type is unreasonably effective in American culture and there are many tendencies which reinforce it.
If we ought to stop talking about anything it is the "Meritocracy". We have the ideal that talented people should rise to the top, but the converse of that is very dangerous: "Because I am powerful, I am competent."
Back in the bad old days the Narcissitic leader who could control the narriative to suit themselves was a male characteristic but now we are seeing some gender equality.
One example is Marissa Meyer who was successful as a Product Manager because Google was successful. However, Yahoo needed a turnaround specialist, not a cult of personality. I guess she'll run for Congress next.
Jurgen Habermas in his excellent book
https://en.wikipedia.org/wiki/Legitimation_crisis
talks about how politics and other powerful people need to invest in legitimacy, otherwise people become ungovernable.
The Republican party is sick because it has pursued legitimacy through making candidates run the guantlet with a large list of "litmus test" questions to get access to funding. One reason Trump won was that he escaped that and put together his own bundle of issues that actually appealed to voters.
Certain prominent Democrats have leaned on the "I am powerful, this is a meritocracy, thus I am deserving" line entirely too much. This reaches the absurd extent that there was only one significant candidate in the Democratic primaries who was actually a Democrat and you find many Democrats who think Clinton lost because she had opposition in the primaries.
To the contrary. If a candidate wins a seriously contested primary it shows a lot about their ability to reach out to people, win elections, etc.