Certain SharePoint features are available only if you're on modern. Are you on modern yet?
SharePoint Framework is a very powerful model for extending SharePoint... in the cloud. On-premises, it's a whole different story.
When you need to create many SharePoint list items, be sure to choose the fastest approach to do it.
Just because you're on-premises today, doesn't mean you will be there tomorrow. And even if your local laws and regulations make it impossible for you to move to the cloud, there are benefits in extending SharePoint in a cloud-ready way.
What version of the SharePoint Framework should you use for your project? 'The latest' seems an easy answer, but there is more to it.