Would it, therefore, not be a good idea to also link to the sub-categories on the homepage?
There are 100 sub-categories in total, so my thinking is that this would dilute the link juice way too much, when it's the categories and posts I only want to rank.
The sub-categories would only be there for users, because clicking on a category currently takes a visitor to a list of posts and not any sub-categories.
1. Just list categories.
2. List both categories and sub-categories.
3. List both but make sub-categories no-follow.
Which one would you choose?