Oh my goodness, SO much adorable. <3 I love how they came out in your style, they're just too cute for words. ;A; I gotta say, Applebloom's pose in the back there is probably my favourite, she's so cute. <3 Gosh your colouring is so perfect. ;w; Amazing work as always Jen
If I had to pick one out of the three, it would be Sweetie.
But they are much better as a group - I doubt Sweetie would be as entertaining without the two others either pulling her or being pulled into ridiculous situations. The group dynamics between those three and the rest of characters is what stands out the most about the CMCs; not really any single one of them specifically.