If you want to actually know about Makhno's military career, I would suggest Belash's book is probably vital.
All the other witnesses were politically motivated. What they wrote about the campaigning was largely second hand and filtered through rose-tinted glasses. Naturally Belash will not be unbiased, but he was at least involved in military decisions, and wasn't writing for an admiring audience.
Apart from Darch, none of the secondary sources in English take any effort to actually consider Makhno's military efforts. They are written by people motivated almost entirely by political concerns (and usually more or less anarchist). They accept at face value almost any statement made about how good his forces were and how they were organised.