Same rules as my 'Favorite Video Game Weapons' list (one game per series, need to have played the game myself, not ranked, any boss can be here for any reason, etc.), only that I won't have any honourable mentions. I also won't be giving them descriptions since frankly, I have trouble articulating why I enjoy these particular fights more then others.

Or rather the bigger issue is the repetiveness of saying "This boss is really challenging and fun", "The music is immaculate", "The setting and atmosphere is incredible", and so forth. And lastly it's to avoid describing spoilers in detail, though if learning the a name for a end game boss fight is too much for you personally, then back out now. I'd understand.