They're all awesome and I would have a lot of trouble saying which is best. Here is what my thoughts are if I was to order them:

#1: My favorite as it has the best rendering of the milkyway.
#Comparision image: This is the one your comparing with, and has the best foreground scene. The milkyway has a bit of a washed out/reddist cast though IMO
#2 and #6: Great milky way renditions.
#3 I love this image, but the milkyway is slightly muted compared to some of the other images.
#5: Looks you had some auroral glow which washes out the sky a little.
#4: Fantastic composition! However, the stars seem a bit out of focus?

Hope you didn't mind my critique :)