Generally the rationale for using noindex
on category and tag pages is that they tend to be near duplicates of each other and of the index page. Avoiding content duplication is a key aim of most SEO strategies. Thus the noindex
approach.
As with most SEO questions, the best answer will come by thinking about what people want.
Do you have the sort of site, and the sort of content, where optimised archive pages for each of your categories would be a useful landing page from search? Or, are your category pages really just something that people use as a means of navigation when already on the site?
If it's the former, you need to design pages in such a way as to be well optimised for the category terms, e.g., with some unique editorial content and so on. If it's the latter, the typical WordPress template page with a noindex
is probably best.
But don't trust me: trust your site. If you're really not sure what's best, experiment and let your analytics data guide you.