A must is for our core values to be aligned: the way they see the world, as in politics religion (or lack thereof in my case), ethics, etc. Anything that might result in coming to a crossroads down the line. I don't want children so I wouldn't be with someone who is hard set on having them. I don't eat animals or animal products so I wouldn't be with someone who does. Above all, I look for kindness in people and I'm very grateful that there is so much of it in my current life partner ๐
I don't think taste is something that has to match, or interests. A general curiosity regarding what your partner likes is great but to me, a shared taste in music or movies is not necessary.