The mallet that is my favorite is sold at japanwoodworker.com. It is called the Katate Kakeya. It comes in 90 mm (46 oz) or 75 mm (31 oz). I think mine is the 46 oz. I love it and do not baby it at all. I have one that lasted for over 6 years or so before it started to show some stress. I have another now and they are both very healthy. Japan Woodworker has some cool stuff that you won't see many other places.
I've never been a fan of the round lignin vitae (sp?) mallets. Just a personal preference. I feel like I can steer my chisel more accurately with the flat face that the Katate has. It also behaves more like a dead blow hammer upon striking, in my observation; less bouncy/lively and more concentrated force delivery. Like I said, just my preference.
Good luck!
Joe