The only difference is that left is more matte and oldschool and this is likely triggering some nostalgia in you.
Some of these look better on the right, some of these look better on the left.
1 right looks significantly better
2 right looks significantly better
3 right, both charming, don't care for either faces, I like the feather but the armor is cooler
4 left, cool asymmetry
5 left, she is prettier and has a cooler outfit
6 left, absolute angel, I want to raise her sucker for blond with white cloths and the short hair from the hat
7 RIGHT! RIGHT ALL THE WAY!
8 right is just significantly better, less stiff, more dynamic, better designed...
9 left, looks like a shonen you would root for
11 left, she looks plain in left, but she looks ugly in the right
12 RIGHT! I love the left, but the right is god tier
13 Left, left has a cuter face, even though I like the costume on the right way more
I do think the faces got worse in some of them, which effected some of it, but all in all the only thing wrong with the right is the heinous crimes of being modern.