I think my ideal Avengers run would probably include some line-up shifts, but...
- Captain America – I feel like this is self-explanatory. He's the soul of the Avengers.
- Songbird – She's well beyond earned it. I'd have her basically be Cap's #2
- Karma – I admit, this idea came to me in response to Hickman pulling Sunspot and Cannonball onto his squad. But I think it could be great. Xi'an tends to get lost amongst the hordes of X-Men and their eighteen thousand telepaths. But the Avengers tend to be short on the telepathic side of the equation. Given she's recently been made into a millionaire (billionaire? I can't recall precisely), she could take over from Stark as being the one with money.
- Black Panther – I mean, he's too cool. And would fill the genius slot.
Then there's sort of the outer circle, the ones who would cycle in and out. I'm not saying they'd all be on there, but, a handful at a time.
- Pod / Enigma – I like the design, and I feel like there's more potential for her.
- Thor – I'm actually tempted to leave him off, because way too often he's functionally irrelevant to whatever Avengers team he's on. But, he's a classic member, and if he was given something more dynamic to actually do...
- Abyss – purely because I like the design. The fate of her and Ex Nihilo is ambiguous...
- Spider-Man – he's best when he's more of an outsider to the team than a core member.
- Hawkeye – both of em.
- Scott Lang
- Captain Marvel – Carol is great, but I think she shines better on the Ultimates.
- Quicksilver – he works great in an ensemble – plenty of other teams too.
- Scarlet Witch – She's cool
- Dark Angel – the Marvel UK characters are underutilized.
- Tiger's Beautiful Daughter – Huh, another one where I just like the design.
- Jennifer Kale – 100% just a pet character of mine. Marvel doesn't really have a totally independent magical woman character. Wanda is very tied to Magneto (retcons aside), Clea is a Doctor Strange character... I think that if they leverage Jennifer right, she could be elevated into her own compelling property
I don't think I'd want to exceed more than around 8-ish members at a time. Too many at one time, and the specific makeup of the team begins to feel inconsequential.
People complain a lot about how "anybody" can be an Avenger now, but I think the team is at its best when it gives underutilized characters a chance to shine. A team that's all big guns might be cool, but you're not going to see any fascinating character development in that. The trick is just that they need to stick to the characters for a while and actually use them, rather than cycle them out constantly.