Personally, I do find hard to think of a personal favourite boss, because I have a bunch of bosses I have particularly enjoyed. Twinrova and Phantom Ganon from Ocarina of Time, Odolwa from Majora's Mask, Ganon from Wind Waker, Argarok from Twilight Princess... and that is not mentioning the DS and 2D games. However if I were to choose the most memorable boss battles of very recent games I would mention Scervo from SS and Ghirahim's lasts phase; which is, hands down, the best boss in the game, at least it is one of the most memorable battles in the series. Jumping platform to platform while performing and Ending Blow has to be something noteworthy, is it?