Is better to use an LMS  or a CMS and a plugin LMS ?

If your goal is to deliver educational courses or training programs, an LMS would be more suited to your needs due to its specific learning management features. If your aim is to create, manage, and publish content to a broader audience, a CMS would be the better choice.

So Moodle or WordPress + LearnPress   (study what you want to do, and what Moodle offers vs LearnPress  (or MasterStudy. e.t.c.)