There are so many possible answers.
The Romantic answer, like Marcelo's one.
The Historical answer; The Polaris, because of its clean and strong look, but it would work with the Black Memovox, or the Deep Sea Alarm, too....
The Elegant answer: The Duo Metre, or a nice Reverso, like the 70eme, the 60eme, or of course, the Reverso Tourbillon skeleton.
The Mad answer: The MMR, a Concept watch housing a traditional complication... Really love this blend.
The Original answer: The Amvox II.
The Superlative answer: The Gyro Tourbillon I or II.
The Innovative answer: The Extrem Lab.
The Artistic answer: The Perpetual skeleton.
The Dream answer: The one which doesn't already exist...
Among all these possibiities, which are not exhaustive, of course, I guess that the answer will depend on WHO you are.
A watch which corresponds to your style of life, a watch to live with, this would be considered as THE favourite watch, IMO....
Best,
Nicolas