What platform has the best 3rd party developer program?

I've built apps for Slack, Airtable, and Procore, and there's been a pretty wide range in quality of review processes.

What platforms have you built on and what was the process like from a review standpoint?

For those interested in what I've experienced:

Slack:
Very mature tooling from a technical standpoint
Fast review cycle (1-2 weeks IIRC)
Low/medium responsiveness

Airtable:
Inconsistent technical maturity. Ranges from low to very high.
Extremely slow review cycle. 12+ weeks.
Extremely low responsiveness.

Procore:
Medium to high technical maturity.
Very slow review cycle. ~4-8 weeks.
Inconsistent responsiveness. Entirely dependent on who your account manager is.