Francis Wheen, "The Life of Karl Marx" - Biography by the English writer in pursuit of the human Marx.
Francis Wiener says in this work that his writings are not biased toward either ideology, but rather portray a "human Marx" who is neither God nor the devil. In other words, he states that he wrote his biography from a "neutral" standpoint.
However, as is the case with all genres, there may be no one more difficult to look at from a "neutral position" than Marx.
I found this biography to be an easy read, but the type of book that must be read with caution.