Dead soft wire is better for pieces that are small or intricate, since the wire will harden as you work with it. Dead soft wire scratches and dents more easily, so you need a more delicate hand, but it allows for more control.
Pro Tip: Hint: Dead soft wire is also used for coiling, crocheting, knitting, and weaving, or to mix with half hard wire in certain situations. Depending on the size (gauge) of the wire, dead soft wire does not hold its shape in stress situations, such as prongs; however, it can be hardened and/or beautifully textured by using a variety of jewelers’ hammers. (answer contributed by Dale “Cougar” Armstrong)
Half hard wire can be better if you won’t be doing a lot of work hardening.
Pro Tip: Hint: Half hard wire will beautifully hold any shape it is bent into and because it will work harden quickly, it is the perfect choice for executing prong designs. Half hard wire forms crisp clean angles.