Loser chooses for crew elimination, else it would be too easy to just pick off an opponent’s Davy Jones very early in the game/etc. The Superbe barely has better killing power, you’re mostly paying the extra points for the valuable speed increase.
I love the Magnifique as well, she was my first 5 master! The French got a lot of good and beautiful 5 masters, which is part of the reason I enjoy playing them as a faction. (favorite ship type and they just look awesome, though almost too pretty for battle sometimes XD)