I'm wondering if in my header the best way to display the subcategories is to click on the categories or displaying the subcategories when roll-overing on it?
Woman, Man and Kids are my categories. Subcategories example: Dress, jeans, tshirt, etc.
Please use the clickable version.
A other solution would be, if the categories are stand alone pages. Example for the Woman category.
When you click on Woman you will visit an overview page for all Woman-stuff. Then it is also okay to display the subcategories as far as you display those on the overview site.
But in general, make the parents clickable!
I read an article yesterday called "Goodbye to 8 Design Elements Whose Time has Come" that talks about this. I recommend you read the entire article, it's not to long. If not, the part about hover state is below.
If you want it to work properly on touch devices you should go with click/tap, not doubt about it.
I think its a better user experience to just display the top level/parent categories and then show sub navigation on those pages. It removes the clutter from the main navigation thus not presenting the visitor with 500 different sub level and sub sub level navigation.
Of course, it depends on the store and the range of products.
But another benefit is this also keeps authority in the most important/top level pages of your website rather than leaking this to so many other deeper category pages.