What are some messaging courses you would recommend?

I'm not sure about courses, but recommend the following books:

1. Positioning: The Battle For Your Mind

2. Building a Storybrand by Donald Miller

3. Win Bigly by Scott Adams

Outside of that, there is no better training than practice. Relook at the positioning on your website, on sales decks and decide whether it is consistent with strategy and if not, then come up with new positioning and messaging. 

Daily life provides a lot of observations on positioning. From TV ad slots, to political campaigns, to billboards, and even Linkedin or Dating profiles. People are always positioning themselves and the companies they represent to win in this world.

Anything from my friends at PMA, hands down. They have a great certification program, and they also offer one-off sessions.

Their Narrative Design Masterclass is coming soon!
https://productmarketingalliance.com/narrative-design-masterclass/

They've also got a great Slack community where Product Marketers can share tips & tricks, and ask each other questions, get gut checks on strategy, etc.

I've taken two professional development courses on messaging (Pragmatic Marketing, Magnetic Speaking Messaging Course), and several marketing courses online and through school. 

My major takeaway from all of these courses is that marketing is about influence, and as a marketer you need to be the strongest advocate of your own work because everyone thinks they can do marketing.

The best way to differentiate yourself as a marketer is to have a point of view of your industry and to create messaging that is authentic to you. Then find creative ways to show your wins to both internal and external audiences. That will take you a long way. 

I would recommend checking out April Dunford's book (she has many interviews / podcasts online as well). She wrote a book called Obviously Awesome. 

https://www.amazon.ca/Obviously-Awesome-Product-Positioning-Customers-ebook/dp/B07PPW5V9C

As for additional courses, I would recommend some storytelling courses. Coursera has a few. This is an area I am researching as well.