Yes. Kainaat IS a better muslimah than saltanat because she wears her hijab. She is also a better muslimah because she offers namaz. I understand that as a non muslim you might have a differing point of view. Which is your own opinion. But islam is quite crystal about its commands. Hijab is not optional in islam. It is enforced on both men and women. You are not forced to wear it because faith can't be forced. But if you are an actual good muslim with the fear of Allah in your heart you will because it is a direct command in the Quran. So yes if you look at it from an Islamic point of view ,kainaat is better. As is evident kainaat relies heavily on her faith. So no wonder she dislikes the fact that saltanat has little to no regard for the teachings of Quran and al hadith.
Infact any pious muslim will instantly say kainaat is a better muslimah as of yet that has been shown in the show. However in the future if kainaat resorts to lying and plotting then she will fall in my esteem. Because both lying and backbiting are major sins in islam.