I wish I had all of them, unfortunately not the case. After 15 years of accumulation I still have no idea of all models. Strange enough I always have preferred T17 to 20F even if the former are rarer.
Yann,
Do you prefer the T17 because of the 60 hour power reserve or is it something else about the T17?
Dall
There was no choice based on the qualities of the caliber. I guess I was more attracted to T17 designs than to 20F designs. It was also probably easier to find T17s in good condition than 20Fs.
I ended up with 5 times more T17 than 20F (counting only the ones in working condition I have some projects watches with 20F calibers).