theme – hook_theme_suggestions_HOOK vs. hook_theme_suggestions_HOOK_alter

Let's say that some people are working on a contrib module (link) to provide some obvious template suggestions that are not covered by the default Twig template name conventions. Display mode for fields, region for blocks, etc.

By habit I would use it hook_theme_suggestions_HOOK_alter. I simply add my suggestions following some logic, done.

This hook allows any module or theme to provide an alternative theme
suggestions of functions or names of templates and reorder or remove
suggestions provided by hook_theme_suggestions_HOOK () or before
Invocations of this hook.

Then I see that there hook_theme_suggestions_HOOK that more or less does the same except for reorder or stirring suggestions But basically looking at its description it does. exactly What that module is supposed to do contrib.

This hook allows the modules to provide an alternative theme function or
suggestions of template names.

And now I wonder which of these hooks should be used at best? Is it totally from us? Are there disadvantages to using the *_alter hook? Better we use the mere suggestion? *_HOOK Allow other modules to intervene later in the process?