I like the change of pose for Rainbow Dash. One of my (unspoken, lol) suggestions for Dash last time was to put her in a more confrontational/confident pose to match her personality. I also like the expression on her face.
I really like the style of Twilight Sparkle. The only thing I would suggest changing for her specifically is that there's something off about her mouth. It might be a bit too high or wide, I'm not sure, but something is off. The other suggestion I would give for both is hair size. It seems like they both have rather large heads and I would scale the tops down a bit, lol. Try drawing a circle with the center resting just above their eyes, and the diameter the width of their face, if that makes sense. That way you have a basic head shape to fit the hair onto. (: