Which communication and presentation course publishers are known for progressive difficulty and native or expert instruction?

A few well-known communication and presentation course publishers that are often associated with progressive difficulty and native/expert instruction include:

• Cambridge University Press – strong on staged skill development, clear progression, and expert-authored materials.
• Oxford University Press – often uses graded, level-based learning with native-speaker materials and professional pedagogical structure.
• Pearson – publishes many communication and presentation programs with step-by-step progression and expert instruction.
• Macmillan Education – known for structured skill-building and materials created by experienced language-teaching specialists.
• Cengage / National Geographic Learning – often features expert-led content and carefully sequenced difficulty levels.
• McGraw-Hill Education – offers presentation and communication training resources with a gradual increase in complexity.
• Kaplan – especially for professional and academic communication, with expert-designed, skill-progressive courses.
• Purdue OWL / university extension publishers – not commercial publishers in the usual sense, but widely respected for expert instruction in communication and presentation skills.

If you want, I can also narrow this down to:

1. publishing houses for ESL/English communication,
2. corporate presentation training publishers, or
3. online course platforms with publisher-backed content.