I've chewed through several different units and would say from my experience...
...That the Blueant Q2 & LG Tone were the best.
...The LG Tone flat out ROCKS!
You can pull an easy 4 hours of talk time on the Q2....
...And I'm guessing 9 hours on the LG Tone.
Where will you use it, for how long each day, do you want it to pipe music into your ear, is style critical... Hard to say what is best without knowing what you want it for.
SoundID Six
Wear mine all day and is very comfortable. Bought it a couple months ago because my 510 got damaged in the rain. Forgot I had it on.
1saleaday.com has it on sale today for $50. Bought mine for more than twice that.
The Plantronics Pro is an excellent device - most people don't know that I'm on a bluetooth device when they call me. I wear it 10-12 hours a day, 6-7 days a week.
The Plantronics Savor looks like it might be a really good device if you are wanting a totally hands free device.