Creating a Categories term store to manage my Wiki Pages Vs creating multiple wikis sub-sites

I want to create a publishing site which have enterprise wiki to store and manage internal procedures for our company, so I find that there are two different approaches which I can follow to organize my wikis:-

1. Create a single Enterprise Wiki Site Collection, and then to organize all my wiki under a term store. so that I will build term store taxonomy where each department will have a separate term set.

2. The second approach is to create a main Enterprise wiki site collection and then create different sub-sites for each department.

So what will be the pros and cons for each approach?, and if each department require different user persimmon on their internal procedure so does this requirement restrict me to go with the second approach so that I can have different permission for each department (in this case different enterprise wiki sub sites)

Best Regards