Trans Loving Trans (TLT), also known as T4T (Trans For Trans) is a term for transgender people who are either exclusively attracted to trans or otherwise non-cis people, or emphasize or prioritize their attraction and relationships with other trans people, celebrating transgender love. TLT can be used in combination with other orientations (for example a TLT lesbian would be a trans woman who prioritizes relationships with other trans women).
The unwillingness to date cis men/women is not because there’s any inherent difference between cis and trans men/women, rather it stems from issues of safety, trauma, oppression, or other personal reasons. One may prefer a trans partner because one would relate to them more. One may also not want to be vulnerable to misconceptions, misgendering, or oppression from a cisgender partner.