It's likely a function of how much $$$ u r willing to spend...
You'll get better range, battery life and connectivity with Bluetooth 2.0 but you'll spend a lot more (>50$).
I've been using the Plantronics 665 for about 2 weeks now and love it. In addition to the normal voice dialing features, it has a smaller size and weight than most competitors. The design is also less obtrusive than others (Hello, Jawbone).
CNet has several good reviews:
Bluetooth Headsets - CNET Reviews
Better yet, wait for Bluetooth 2.1 and you'll get 5x the battery life.