Aizawa definitely had a favourite student. And he has multiple reasons for that. The main one being that he just saw her as his daughter. Not as a normal student. And they help each other.

Yuri was sitting on his lap while he graded papers, lying comfortably with her eyes closed as he held her with one arm, and graded with the other.

"What the-... Baby girl?" He whispered and looked at her. "Can you explain your thought process for question four?"