3-Step Pliers
These are my favorite pliers for wire working. Available through many online and local bead stores, they are invaluable in creating wire loops in consistent sizes.
One jaw on the pliers has three separate sections to make small, medium and large loops. The other jaw is either curved or flat; either are acceptable for wire working.
When using pliers with jaws that have not been coated with rubber, nylon or plastic, be sure to carefully examine the pliers periodically for nicks or dents that may damage your wire. Also, don't grip too tightly...your hands will tire more easily and you will be more apt to damage wire inadvertently.