Sorry, I've just realized the Booking.com font stack is too limited and doesn't take into account enough system fonts.
In a design perspective I'm in favor of the simpler implementation where all fonts look closer between devices, but the real goal should be having them closer to the system fonts. So I'd say to actually make a decision an screenshot of the Ubuntu one where other UI elements of the system are visible would be needed.
Reverts drupalux/seven#54
Sorry, I've just realized the Booking.com font stack is too limited and doesn't take into account enough system fonts. In a design perspective I'm in favor of the simpler implementation where all fonts look closer between devices, but the real goal should be having them closer to the system fonts. So I'd say to actually make a decision an screenshot of the Ubuntu one where other UI elements of the system are visible would be needed.