The Top 6 Contenders

1) Icarus led a team of super-human immortals. I think he would be too demanding and not understanding enough of human foibles. I reject him as the new leader.

2) CPT Marvel wasn't involved when she should have been, before Thanos had the chance to snap his fingers. She's too busy elsewhere and wouldn't give the Avengers the due diligence a leader needs to give. Rejected.

3) Spiderman is too young. He still needs to be the 'friendly neighborhood Spiderman' a while longer. Groom him for the role in the future but don't give it to him now. Rejected.

4) Dr. Strange has other fish to fry with his leadership of the band of monks or whatever that cabal is. While there are people in real life who lead, or are part of the leadership of, different corporations, I don't think that Strange would be able to adequately divide his attentions, not even using magic, though he probably could. Story-wise, I don't think it's a good idea. On the article: seriously, guys, racist and sexist in one sentence? That's not a reason to reject anyone for the leadership position. Go on the character's character and skills!

5) Professor Hulk. Why not? He's grown, as shown by the integration of Hulk and Banner. He's been through a lot and proven himself. He has the time, he has no other commitments like Strange does, he's a mature adult, and as a professor he's likely to be able to give some rudimentary counseling. He's smart as heck and his confidence has grown yet hasn't become arrogance. Possible.

6) Sam Wilson is my choice. On the surface he looks like he wouldn't be aggressive enough to do the honors but I think that's just a quietness that cloaks strength. He's military so he understands the use and the need for discipline, something I think Peter Parker has yet to fully learn and understand. He's been on his back foot several times so he'd be understanding of failure while still being able to encourage improvement, and able to suggest aids and mentors to facilitate that, unlike Icarus. He has experience in counseling due to his work with veterans. As a military officer he's versed in tactics and strategy, which all officers need to learn in order to advance.

My top three:
Sam Wilson
Professor Hulk
Dr. Strange

I'd also pick Black Widow but she died in Endgame. If they'd drag her from an alternate universe the way they dragged Gamora, I'd choose her for second spot and bump Hulk and Strange down a notch. She has experience, discipline, and she's been an Avenger since the first of the movies, or since Ironman... 2? 3? She's practical and empathetic so would do well in interpersonal relationships. She can delegate, an advantage for a leader. Everyone on the team both respect and like her so there would be no challenges. I think any other pick would elicit challenge from one quarter or another, all with good reasons. As second choice, I think she would work well with Sam Wilson as leader, enabling him to worry about more administrative stuff while taking on the more mundane day-to-day ably while being able to step into his shoes when he isn't available. If the Multiverse makes it possible, I'd say bring back Black Widow. For the actress, who isn't getting any younger and may need to curb the extremely physical stuff in future, being at HQ and directing things would lengthen the time she stays in the MCU.

A good leader doesn't need to show strength, it just exudes from (him/her, choose for whichever you're talking about). As for the kindness/weakness quote, how about Al Capone? www.goodreads.com/quotes/922378-don-t-mistake-my-kindness-for-weakness-i-am-kind-to

The BW people know is Natasha Romanov (Romanoff?) so that's the one I mean. They may all have the training and various useful experiences related to it but she's the one the Avengers know and have worked with and is the one the reader/viewer knows.

Sam comes across as gentle and kind, hence trustworthy. This is a good quality in a leader. I think he can do the job.