Choosing size, neck and stopper
The first question is what the carafe is for. For water on the table you want a straight shape with a narrow base, which takes up little room and fits easily in the fridge door; the Bacchus sizes from 0.25 to 1 litre are the standard there. For house wine by the quarter or half litre, take the same shape in a smaller size, ideally with a line marking where the measure sits. For wine that needs to breathe, choose a wide, flat base instead, because the amount of wine touching air decides how quickly it opens up.
Then look at the neck and the stopper. A carafe without a stopper is meant for use within an hour or two, while a carafe with a ground or airtight stopper keeps spirits good for weeks and stops the aroma seeping into the sideboard. The whisky models of 70 to 96 cl fall into that group. Finally, look at the weight: cut crystal is heavier and better looking, but a light hospitality carafe can be poured full with one hand, and that counts when you are serving a table of ten.