Amazon

Interesting problems, complex designs, exposure to new technologies – but highly dependent on the team.

Promotions are very political (even though they claim merit-based) and highly dependent on your manager and how he/she will present your projects (even though they claim it's more on you).

Then it is determined by how much you've won over the x number of engineers you've worked with.

If your manager changes (my team has had 4 managers over the past 2 years), it effectively resets your promotion process, which is not ideal.

Give interesting and high-visibility projects to developers earlier. Also, start promotion talks and steps earlier. Don't wait until your team members are upset and leave right after promotion because they've felt underappreciated and underpaid for a long time.