So far Cho (9) has the most, but since I've been playing her for months with no personality profile outlined, I'm going off mainly how I've played her, with some differences.
Yuki (8) has the second most traits, with Mikumi and Miyako tying for a close third (7). So far the only ones I /need/ more traits with are Raphael and Aurek, but I had some stuff done for them already at home, so I stopped at 5.
Also, I've noticed a lot of my characters are either lacking in confidence or extremely reserved/distant/isolated/guarded... o_o; Weird. Maybe I should app Subaru. n.n;