[astrallionheart]

No surprise for me Ukitake is ranked lower than Byakuya, Yoruichi already more or less stated that nobody on the bridge at the time really had a chance against Byakuya, despite two of them being his "seniors".

Yamamoto probably considers him and Shunsui his best students but Ukitake has already shown to be pretty much useless in real combat situations given his medical condition.

Here's a different way to measure their power since this serious is dominated by zanjutsu:

Ranked by Combat Power (Offense/Defense/Mobility)

1. Yamamoto - 100
2. Aizen - 93.3
3. Shunsui - 90
4. Byakuya - 86.6
5. Unohana - 83.3
5. Hitsugaya - 83.3
5. Ukitake - 83.3
8. Komamura - 80
8. Kenpachi - 80
8.Gin - 80
8.Soi Fong - 80
12.Tosen - 73.3
13.Mayuri - 60