I have argued this before and I will argue it again: Mylene is the main character of Macross 7. She is the character that is new to all the weirdness, she is the one people explain things to, she is the audience avatar, she is the character that it is easy to relate to, especially if you are 15 or whatever as the show's intended audience was. She is the one the love triangle focuses on.
Basara is kind of in the position of Roy combined with Misa. He is the older, more skilled pilot who is kind of a mentor, but he is also a somewhat cold, driven, and emotionally detached love interest. Yes, he is the popular singer like Minmay, but his personality is way more like Misa.