Regarding senior to staff growth - What kind of team is best?

It depends. There's a few other variables in play too:

• How much scope/person does the team have on a yearly basis?
• What is the relationship between management and the ICs? Is management already committed to promoting and growing specifix individuals?

Each of these variables can drastically change the path to Staff for each option. To show how these variables can remove the path to Staff in each scenario.

1. The team of extremely talented engineers could be mostly senior and staff. The team is top heavy & scope likely flows to the staff engineers first, then the experienced senior engineers, then the new senior engineer (you). You are fighting for scope more than actively working & can end up with a low rating due to a lack of work to prove impact.
2. A team of decent (but hardworking talent) might be easier to stand out, but there could already be senior engineer who's worked with management on working towards their staff promotion. Scope can be limited, so scope will be given to them first. You need to wait 6 months after this individual's staff promotion (promotion budgets are limited and staff promos cost $$$). After their promo, there is not enough scope to support another staff promo. Scope flows to the staff engineer first (to prioritize maximizing their value), and then to you with the staff-level scope removed.

This is diverging significantly from your original question, but the better variable to consider imo is "what will my responsibilities look like if I were to join the team"? If the baseline of scope that you start with isn't the higher end of senior, you'll likely need to take more time to prove your worth to get that scope. If you're joining as a new senior eng at FAANG from another company & not internal transfering to another team, you'll need to incur ~1 year of overhead to build up relationships between management, your team, and your xfn stakeholders before there's clear conviction that you can start working to Staff. But if you're given a stronger baseline of scope off the bat or bringing in reputation over as an internal transfer, the overhead will be significantly lower.

As I talk about in-depth in my promotion course, I'm a strong believer in maximizing your skills given that promotion/level are lagging indicators. Even if your current team isn't right for promotion, those skills will stay with you as you switch teams/companies. Because of this, Team 1 is far better for promotion as you'll learn more from better engineers.

I don't think Team 2 has real benefit as promotions are generally calculated at the organization level (think Director or Senior Director of Engineering), not the immediate team level (i.e. you and everyone else who reports to your manager). So yeah, you can stand out among your team of okay-ish engineers, but it's not like that gives you an easier promotion. This feels like trying to game the system.

What's more important are the levels. If you're on a team where there's already 3 Staff Engineers or something, it will be very hard to find Staff scope. If you're on a team with prodigy engineers but they're all juniors, that's not really infringing on your ability to find Staff scope.

In fact, the talent angle helps you even more for promotion on top of the general learning:

1. If your team has genius Staff Engineers, their goal is to get to Senior Staff/Principal. They will do this by delegating their Staff scope to more junior engineers than them (like you!), so they can create that Senior Staff/Principal scope. This is the "scope pyramid" that I break down in my promotion course here: https://www.jointaro.com/course/nail-your-promotion-as-a-software-engineer/you-need-more-junior-teammates/
2. If your team has genius junior and mid-level engineers, you can ascend past your Senior scope by delegating it to them. Since they're amazing engineers, you don't need to worry about mediocre work, which wouldn't be the case if they were just sort of okay. This allow you to show Staff scope.

When it comes to a company as rigorous as FAANG, it's almost impossible to find a shortcut. You need to put in the work and genuinely get way, way better as a software engineer to get promoted.