It's great to see that she could be so contented and carefree at some point in her life. Sure, Princess Celestia probably feels inner peace most of the time, but she's also shouldering a lot of weight. Perhaps she can think back to being a pretty lil' filly and napping among the lovely flowers now and again.
The only thing that looks weird to me is that her aura/outer glow affects her outlines so much that they clash against her inner lines. Maybe it's just a matter of degree, and always remember that my color vision isn't that great. The effect looks fantastic on the flowers and grass, making it all seem very dreamy. It makes perfect sense to keep her outlines from clashing against all that too. It could just be a matter of degree because if I push my screen way back and slouch (boosting the contrast?) it looks perfectly gorgeous.
It pains me to critique something that makes me feel so warm and happy because I really do love it.
Both of those styles you mention are terrific for what they are, case by case. Just go with whichever style you feel like depending on your mood and what the final product is: for silly comics and shorts, then go with the bold comic, but for your highly emotional and expressive pieces I can't imagine anything but the finished style with visual depth to go along with the feelings. So if you make me choose then it's the latter.
Then keep doing both, depending on the mood of the drawing and the mood you're in personally. Your comics are downright hilarious and look good in the comics style, and your finished pieces are extremely moving and beautiful as all Pony Heaven.
Being a stylistic polymorph, and an exceptionally skilled one at that, is something that even the most fantastic artists envy.