Pyrex 1, 1.5, 2.5 qt tempered glass

Because it is the one thing steel cannot do, and six of the thirteen sets here are steel. Cuisinart and Viking both publish "refrigerator and freezer safe" and stop there — correctly, because metal in a microwave reflects rather than transmits, which at best heats nothing and at worst arcs. Glass transmits. So with a glass bowl you mix the batter, cover it, chill it, and then melt the butter or warm the milk in the same bowl — one bowl instead of two, and one fewer thing to wash. The sets that also claim microwave safety here are the plastic ones: Zulay and COOK WITH COLOR. This is the honest reason to own glass bowls alongside steel rather than instead of them.

For baking, yes. This is the smallest maximum capacity on the shelf, and the useful comparison is what a batter needs: a standard two-layer cake wants a bowl of 4 to 5 quarts so you can beat without it climbing the sides. Cuisinart and OXO both reach 5 qt, KitchenAid and Ziruma 4.5, and COOK WITH COLOR 5.8 qt — the largest here. What a 1, 1.5 and 2.5 quart set is genuinely good for is mise en place: an egg wash, a cup of chopped herbs, a dressing, a salad for two. Pyrex’s own Colors set reaches 4.5 qt for $17 more and adds lids. If this is to be your only set, buy that one.

Heavy, and Pyrex does not publish it here — but its own Colors set does, and the figure is instructive: 4,019 g (141.8 oz) for three bowls and their lids, which is roughly 1.3 kg (2.9 lb) a bowl. For comparison, Cuisinart’s three stainless bowls weigh 1,769 g (62.4 oz) together. That mass has one advantage and two costs. The advantage is stability: a heavy bowl resists spinning, which partly makes up for the fact that this set has no non-slip base where six sets here do. The costs are that a full 2.5 qt glass bowl is a real lift, and that glass breaks — tempered glass is strong but it fails suddenly and completely, where a dented steel bowl carries on.