For home use on small quantities, on cilantro and parsley, I just hold the base of the stem in my left hand, and pinch my right thumb, index, and middle finger around the stem, then using my left hand, pull the stem away from my pinched fingers, which usually removes the leaves fairly quickly. Then I'll just run my knife through the leaves. If I've got to use the whole bunch, I don't worry about removing the stems. I'll just chiffonade the whole bunch, then chop the slivers.
You want some work? Try chopping enough parsley to garnish the plates of a plated party for 200. Whew! I do the chiffonade method as above, usually 2 - 3 bunches at a time, and will use two or three chef's knives at the same time. I use knives that are the same length, and preferably with flat-sided handles. I'll wrap my fingers and thumb around both handles, and slip my index finger between the blades. For three knives, I also slip my middle finger between the blades. You've got to have big hands to do this, plus some gripping strength. Of course, this suffers from stuff getting stuck between the blades, like a double-bladed mezzaluna. It still takes me 15 - 20 minutes to chop that much parsley, but it's better than the 45 minutes that a single knife would take.