There’s a matter that I really need some help and advice for.

I have met a religious sister, I don’t seem to like her looks even though I have tried to force myself, because of the great person she is, I still keep wishing she looked different.
What can I do in this case?

You know by nature Human being is the only creation of Allah (swt) never get satisfied in this world but In ilum Irfan (Mysticism) it has said this very nature of us is because actually we are not from here. We (our soul) is from other world and the body is from here only therefore we are always in finding something better and best and actually that thing is God but as we are so much used to with material world we are looking God in matter.

Why I told you this because:
Because any woman who is the most beautiful person in this world, if you choose her as you wife, after few time she will become very very common woman as if she is one of the thousands woman in your area while for others she will be same. Why? I can’t say God forbid you would be tired of her, no Nauzobillah but because she is now in your possession and here by very human nature when overpower something or acquire something, it automatically feels valueless.
But no one can deny this fact also that because you are going to live her so ofcourse she must be attractive and good looking as you have imagined about your future life partner. So you have right to select her or di select her. Even Islamic Shariya has given you this authority.

But again for example if have selected a beautiful woman in comparison to her and if your ideas and would not matched with her then really you will miss her. Because we are not 24×7 in the mood of romance rather most of the time what we always need is one's character and behavior especially those who is going live with us under one roof.

And then rest is in the Authority of Allah (swt) he creates love and affection in the hearts of a spouse according to the Holy Quran:

وَمِنْ آيَاتِهِ أَنْ خَلَقَ لَكُم مِّنْ أَنفُسِكُمْ أَزْوَاجًا لِّتَسْكُنُوا إِلَيْهَا وَجَعَلَ بَيْنَكُم مَّوَدَّةً وَرَحْمَةً إِنَّ فِي ذَٰلِكَ لَآيَاتٍ لِّقَوْمٍ يَتَفَكَّرُونَ

And one of His signs is that He created mates for you from yourselves that you may find rest in them, and He put between you love and compassion; most surely there are signs in this for a people who reflect.(30:21)

So think freely and then Tawakkal on Allah.