Question about sitewide links and image links

I just wanted to get some opinions on two different types of links –

1.Sitewide links – I know generally these type of links are not a good idea any more because they can be a bit spammy, but what are your thoughts?

2.Image links – same question, how much difference is there in power between a contextual link or a link using some anchor text and an image link (Aside from that fact that its not targeting a specific keyword, just talking purely about the power of the link itself.

I have a…

Question about sitewide links and image links