What little I have red in Herodotus was very non-judgemental about the Persians. Certainly he was pro-Greek but he did try to tell history from the way he thought it happened.
The HistoriesIt was the grandfather of the Artayctes, one Artembares by name, who suggested to the Persians a proposal which they readily embraced, and thus urged upon Cyrus: "Since Jove," they said, "has overthrown Astyages, and given the rule to the Persians, and to thee chiefly, O Cyrus! come now, let us quit this land wherein we dwell -- for it is a scant land and a rugged -- and let us choose ourselves some other better country. Many such lie around us, some nearer, some further off: if we take one of these, men will admire us far more than they do now. Who that had the power would not so act? And when shall we have a fairer time than now, when we are lords of so many nations, and rule all Asia?" Then Cyrus, who did not greatly esteem the counsel, told them, -- "they might do so, if they liked -- but he warned them not to expect in that case to continue rulers, but to prepare for being ruled by others -- soft countries gave birth to soft men -- there was no region which produced very delightful fruits, and at the same time men of a warlike spirit." So the Persians departed with altered minds, confessing that Cyrus was wiser than they; and chose rather to dwell in a churlish land, and exercise lordship, than to cultivate plains, and be the slaves of others.
by Herodotus
Translated by George Rawlinson