I searched through all crossover pictures but I didn’t see this comparison yet so… DISCUSS! I thought it’d be interesting.
 
Twilight - Herma Mora of forbidden knowledge or Azura of Dawn & Dusk?  
Rarity - Sanguine of passion and debauchery seems fitting.  
Pinkie - Both Manic and Demented, she’s the perfect fit for the Isles.  
Applejack - Tough one. Her domination of animals made me think of Hircine, nothing else.  
Fluttershy - Meridia, prince of the living.  
Rainbow Dash - Also tough but pride and ambition are characteristics of both her and Dagon.  
Luna - Nocturnal, prince of the night or Vaermina the prince of dreams & nightmares?  
Celestia - Molag Bal the dominator or Mephala the webspinner?