I have to admit, the Jawbone is the only headset I've used. And I didn't pay anything for it. Also, I use it about five times a year. With that said, I have no complaints, and the sound isolation is amazing.
I had a Jawbone II and from the user reviews that one rates slightly lower, so maybe it's worse than the original version.
I guess it's a love it or hate it device. In the
user reviews on CNet some people rave about it and the others seem to hate it. The sound isolation only works if the headset is positioned exactly right. If the rubber stub is not touching your jaw, your voice get's suppressed. In my case I guess it didn't fit properly to put the stub on my jaw.
Apart from the fitting problem and resulting poor sound, I had most problems with it losing BT connection when not in use. I try to answer a call on the headset only to find out that the headset is no longer connected. Then I need to reconnect the headset and by the time it does connect, the call is gone. Or it would simply be off due to an empty battery.
I had a Sony Ericsson headset with a display. Showed who is calling on the display and otherwise the battery remaining. Trouble was that I couldn't use it properly for voice dial in the car (too much noise I guess).
I say a BT headset should have 4 buttons (on/off,accept call/make call,volume+,volume-), should show that it's connected or not, should give some indication of it's battery life, should stay in your ear, should allow people on the other side hear what you say
Now I have a Jabra BT530. Some sort of noise suppression, but it actually seems to make background noises during quiet periods louder due to it's "volume leveling". When speaking it works fine. Again a headset where people complain about the fit. Luckily it fits fine for me. It also works as a mono headphone for listening to music. I don't use it for listening to music, but for language courses or audio books it's perfect.
The BT530 can also connect to two phones at the same time. I connect it to the DECT phone (Bluetooth model) in my office and my cell phone. When either phone rings I can take the call on the headset. If you use Skype, you can use it as a headset for that too. So it could connect to a PC and a cell phone.
I've seen other people swear by the BlueAnt z9i. I was tempted, but I didn't like the complains about it's noise suppresion and the short BT range
There wasn't a single headset that I was really thrilled by. They all seem to have some negative aspects as well. I guess the trick is to find the headset with the least negatives that bother you.