Mane 6's maturity in order?

[Wind Chaser 4,768]

This is a tricky question, because although the definition of "maturity" is clear, its implementation is subjective. For these characters, not only do their nature as dynamic, well-defined characters make this a bit difficult, but also the varying interpretations by different writers. Notably, some writers are better at following continuity than others, and still others portray reasonable character flaws in such an exaggerated manner that it can be seen as out-of-character.

 

Based on criteria of how much they've learned and grown throughout the series, how well they've retained their lessons, and how far they've come in overcoming basic personality flaws, here's how I'd list it:

 

Applejack (very astute and level-headed, great leader, overcoming her stubbornness)

Twilight Sparkle (continuously evolving confidence and skill since series premiere)

Rainbow Dash (occasionally very brash and arrogant, but an amazingly supportive and humble role model otherwise)

Rarity (occasional drama queen and gold-digging tendencies, but still very sensible)

Pinkie Pie (values the feelings of others, though she may not always understand them, and knows herself very well)

Fluttershy (level-headed, but is relatively stagnant in trying to overcome her shy tendencies)