Rarity has shot up my list a lot, I think. She's just been plain fun to watch all season. I think it goes something like this:
1. Twilight Sparkle
2. Princess Luna
3. Rarity
4. Fluttershy
5. Applejack
6. Spike
7. The Cutie Mark Crusaders
8. Pinkie Pie
9. Rainbow Dash
10. Princess Cadance
11. Princess Celestia
And honestly, the biggest reason Celestia has taken a tumble like that is that she was barely in this season. Also Pinkie, despite having one of the best episodes this season in Pinkie Pride, just seems like she grown stagnant. I'd like to see something new with her soon. Same with Rainbow Dash. Of course, despite having them ranked like this, the difference between top and bottom is pretty small. I like them all still.
And yeah, Twilight still holds the number one spot for me. She might have slipped a bit before the finale... and then the Tirek fight happened. That was just nuts, but very fun to watch. "Oh, Twilight is angry now! She's going to- WHOA!!! She's doing WHAT?!" As long as she keeps being adorkable and then pulling out all the stops for when things get serious, she's going to be quite hard to unseat from my top spot.