I have several (who doesn't?)
1. Veritas Cabinetmakers mallet (Lee Valley). Brass head with wood inserts. 11" handle. Useful for chopping all but the smallest motises. Well balanced and nice open swing length. Also useful for "encouraging" a reluctant joint.
2. Veritas Journeyman's brass mallet (Lee Valley). 1 1/4 lb. overall. Useful in small or precise work, tight spaces or corners where you don't the room to swing and precision is more important that heft
3. Brass carvers mallet with brass head and wood handle (purchased from Highland Woodworking). 2 lbs. 9" length. More precise and less bulky than the standard beech carpenter's mallet. 2 lbs. concentrated in a 1 1/2" diameter brass head can exert quite a bit of force if you're not careful
4. Carver's mallet. 20 oz. Polyurethane covered head with wood handle (available just about anywhere). The polyurethane "gives" a little, so it has a more "cushiony" strike. I don't use it as much but it comes in handy when you're chiseling hard wood with little spring
Your choice(s) may come down to what you're most comfortable using. For the kind of work I do, I like round headed mallets, especially with brass heads. The round head means I can use just about any part of the striking surface which allows me to concentrate on the workpiece, not the mallet head position. Next would be the Veritas Cabinetmaker's mallet because of it's balance and swing (and the wood inserts are kind to your chisel handles and more forgiving to surrounding workpiece surfaces). But you might prefer a traditional mallet such as the carpenter's beech mallet.
Hope this helps a little.
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