Never liked the Mirror Episodes, it was always all back stabbing all the time, I keep wondering how any of them managed an Empire.
I liked the Living Witness depiction which has the Mirror Theme when it came to humans with some key differences.
Mirror Mirror however was the best if I had to choose one.
1. A Chain of Command, Janeway was in charge and no one challenged her for power. People gave their opinions freely and she listened. Despite insults and brawls between the crew when it camed to doing a job it was god damned clockwork.
2. Federation styled ideals. Besides Paris calling Neelix a hedgehog while they traded insults every race worked together, there wasn't really xenophobia. In Mirror Episodes you know what races are ahead and who is reluctant to serve. In Voyager if your part of the crew you are part of it. I like to think the whole imagined federation worked like that. If you are part of the Feds you are in, if you aren't get in now or else. Sort of like Micheal Eddington's speech to Sisko about how the Federation is worse then the Borg cranked up to Eleven and actually using Borg as a side bonus.
3. Leather Gloves.
Definitely the best evil universe in my opinion, shame the whole Mirrorverse wasn't like that instead of back stabbing and ugh, the Alliance.