Just to remind you,
the best watchs are the first one and the last one,
because these two can sleep in once, one is waking up before the other and the other one sleeps a bit later. The other turns imply more tiredness, because your character has to sleep a bit, wake up and sleep again which is not very comfortable !
so, see what kind of sleeper your character is, do you prefer be awake early in the morning, before dawn or do you prefer to sleep late after twilight... of course I'm sure some night caste characters would be happy to wake up in the middle of the night : )
now, if you have useful charms you think your character uses every watch it is here you tell me !