For a primary source, there is:

• Bahāʼ al-Dīn Ibn Shaddād ; translated by D.S. Richards, The rare and excellent history of Saladin, or, al-Nawādir al-Sulṭāniyya wa'l-Maḥāsin al-Yūsufiyya, Routledge, 2002. https://www.amazon.com/al-Nawadir-al-Sultaniyya-wal-Mahasin-al-Yusufiyya-Translation/dp/0754633810/

The writer worked for Saladin, and is very pro-Saladin.

There are a few relatively recent biographies of Saladin. I liked:

• Anne-Marie Eddé, Saladin, Belknap Press, 2011.

Eddé gives good coverage to Saladin's context - the politics and economics that partly drove a lot of his military decisions. The biographies by Geoffrey Hindley and John Man are shorter, and both are more aimed at the popular market (but IMO Eddé should be quite readable for the interested non-academic reader).