Footer links are very common on the internet to seal partnerships between different websites.
However, although there is volume due to the fact that being present in a footer implies a backlink on all indexed pages, the footer link is weighted by Google’s algorithm.
In addition, Matt Cutts recently announced that footerlinks may appear unnatural and may be likely to be more controlled than traditional links in content.
Links in the content give a semantic structure to the link, it is much more powerful thanks to the topical ‘context’ that emerges from its location. It is therefore much better than a footer link.