Very cool covers @Richard! I really like all three!
#1 really reminds me of the Rider-Waite tarot deck (my personal favorite deck) and has some great color and symbolism. It also has a more lighthearted, old school Hermetic Order of the Golden Dawn, classic feel.
#2 is much darker and sinister. Has a very "Diablo" feel which is very cool--just different from #1’s colorful motif. #2 is not an "old school" feel but REALLY OLD SCHOOL, like Kabbalah and Necronomicon old school!
#3 is a great character cover. I could see it being a series cover for future books, too. Possibly showing Mike’s evolution over multiple books and the world around him changes.
Ultimately I feel that I feel #1 and #2 are the most unique, but as far as favorites, that is a tough one. I guess it all depends on if you want to do for a lighter feel #1, a darker/sinister feel #2, or a character driven feel #3. I think each direction is a strong one!