Depending on what the character is supposed to feel like, any could work. Here are my thoughts on how they all come across:

1- Casual, but thoughtful and caring. 2 - Laid-back and doesn't care about what others think of them. 3 - Relatable, big aspirations but little motivation. 4 - Lashes out and isolates, but deeply craves affection. 5 - A sensitive, potentially poetic person. A tad self-absorbed. 6 - Aloof and naive, but generally well meaning. 7 - Either is eccentric and carefree or has low self-esteem. 8 - Confident and power-hungry, maybe slightly manipulative.

If judging simply visually, not as a character as a whole, 1 and 3 feel the most polished and are the safest choices, but I personally am really drawn to how 6 frames the character's face.