So, you say you have a website with at least four web pages; home (or landing) page, about, contact, and pricing. Now you need to add at least one more web page … a blog.
Your main web pages may be HTML pages, and you ask is HTML or WordPress better to use. The easiest style for a blog that I have found to use is WordPress. You can easily have WordPress installed in a subdirectory (folder) on your present website.
You don’t need to label your blog as such on your navigation bar. Try being creative