Reciprocal links (especially site wide) are not as efficient compared to several years ago.
Nowadays, a good link exchange would be a text link from a post content (in the beginning if possible) by using your brand names as anchor text (to make the link almost natural). The two links can point to the home page of the other site:
- One link from a blog post of the site A pointing to the home page of the site B
- One link from a blog post of the site B pointing to the home page of the site A
Moreover, make sure the theme of the two websites is close as possible and these links can help visitors of the websites.
Otherwise, using keywords as anchor text for the links can be penalizing if you have many links like this; that's why I advise you to use your brand names.