Short Stories Volume Two Cover Art

I am making a second set of short stories, but I need some help with choosing the cover art. I made six available options. Wing Rainbow in "Wing Mario Over the Rainbow", Pinkie in "Tick Tock Clock", Sunset in front of the boss pipe for "Bowser in the Sky", Rarity in front of the Mirror on the second floor of Peach's Castle, Twilight with the Owl in "Whomp's Fortress", and Applejack in "Tall, Tall Mountain". The pictures can be found here. http://lucky-ness21.deviantart.com/gallery/?catpath=scraps