What are the best courses to further my project management position?
It really depends on your current expertise and education on project management.
If you are pursuing PMBOK methodology, courses regarding PMBOK handbook is a must.
Furthermore, these topics are being on trend in recent years:
Communication in Project Management
Chaotic Project Management
Project Coordination in lean environment
As a project manager, the most important thing to know is a balance combination of operation management and strategic management. Consequently, taking the essential courses of both can help too.
Lastly, topics such as finance, accounting, organization behavior and human resources, and supply chain management are great for any successful project manager.