The link endures and gets your operation identified as 1 of X businesses in the niche. Obviously, your ideal is to have all your inbound links well positioned with very positive reviews in an enduring place. It's why the Top 25 Recruiters list works so well as a traffic generator for the Websites on the list. It can be as simple as a trade of links and a simple cross-promotion agreement to complex revenue sharing arrangements. There are, equally obviously, many shades of link types inside the matrix.
Nothing really fits solidly into any of the categories.
There's also the question of the volume of traffic generated by the link. The same link on a site that gets 10 visitors a week is not worth much effort. Given the complexity of the Web in it's current form, we generally argue that the optimal approach is to create the largest number possible of inbound links. So, effectively, you continually refine your incoming traffic as a way of defining your demographic. Finally, there is the question of site design and your inventory of content.