My boss ratings would go as follows:
Most fun to beat: Ultima Weapon (NOT Omeaga) & Braska's final aeon
Hardest: Yunalessca
Koolest looking & most anoying: Evrae
Easyest: Evrae Altana
Requied Most Stratagy:Spectral Keeper & Last battle with Sin (where u get pulled in)
Oddest Looking: Yu Yevon
Well, thats just me! I judge everything