50.000+ Students: Teachable vs Thinkific vs ...

I need to migrate 50.000+ course students to a new platform and I narrowed my choices down to these Teachable, Thinkific, LearnWorlds. Has anyone experience with both of these platforms?

What I am NOT looking for:

  • email marketing, because I already have my own newsletter
  • landing page, because I have my own landing page

Must haves:

  • EDIT: low fees
  • coupons
  • certificates
  • affiliate marketing
    • nice to have:
      • self sign up of affiliates by sending them a link
      • automatic payouts
  • one-click checkout experience

Nice to have:

  • instalments for students for high priced courses
  • VAT handling
  • group invites (e.g. organizations)
  • purchasing power parity which givers students in third world countries automatic discounts
  • automatic video transscripts
  • video dubbing for multi language support
  • ebook integration
    • not only downloading, but also reading directly in the platform
    • plus: perhaps also ebook generation by using markdown

There is one more thing that would be important:

I want to be able to sell a two-tiered course. Meaning: there are two courses A and B where course B follows course A in a linear learning experience. It is possible to buy course A without course B but not the other way around. So in the end there should be 3 options for a student:

  • buy only course A for $200
  • buy course A and B for $400
  • buy course A for $200 and upgrade to the full bundle by paying the difference of $200

I thought the later may only be possible in Thinkific with their "Create private & hidden courses" and "Bundle with courses" , but I am not sure.

Looking forward to your advice!