The choice is yours. If you’re new to Web site development you might choose to go with type 1 to start with, and then gradually work your way through types two and three before eventually reaching type 4.
If there are not many sites to link to in your particular niche you might decide to stick with type 1 or maybe type 2.
If on the other hand you’re an experienced webmaster you might decide to take the time to master type 4 and give your site a major boost in page count without having to spend weeks writing hundreds of thousands of words of new copy.
Also, it’s worth remembering how having an extensive external links page structure on your site can turn you from just being a run-of-the-mill site into being a hub site within a particular niche. It gives you the potential to become the go-to-site when anyone is searching for information on that particular niche.