Not going to claim the best, but it does work:
Generic BCK-08 receiver, not sure if the microphone part works since I am only using it as a wireless link to other devices:http://www.dealextreme.com/p/bck-08-blu ... ndby-47312http://www.lightinthebox.com/Bluetooth- ... 76708.html
For $13.00 USD hard to go wrong if you want wireless headphones or short distance wireless link to other AV equipment. Ordered a second unit last night for my car stereo aux. input.
I've always like the concept of these (i.e., something that you can plug your selected headphones into). I use Shure SE-110's because I think they sound good and they provide good noise isolation. That's a big issue for me since I live in NYC, which is one of the world capital's of background noise.
Anyway, the first Bluetooth headset adapter of this type I ever tried was the BCK-08 referenced above from DealExtreme. It sounded OK, but my battery only lasted 2-2.5 hours, and it fell apart after two weeks.
I've since tried:
1) Acoustic Research ARWH1 http://www.amazon.com/Acoustic-Research ... 533&sr=8-1
I've had this one for a while. Was US$30 when I bought it.
- decent battery life
- extremely annoying background hiss
- 8-wire USB charging interface is quite uncommon, at least amongst the devices and cables I have
2) Sonorix C3 http://www.amazon.com/Sonorix-Bluetooth ... 652&sr=1-1
Just got this one a few weeks ago. ~US$50.
- very good battery life (6-8 hours)
- pairs to multiple devices with no issues (A70 and BB Tour)
- good sound
- interesting design which allows more flexibility of clipping onto clothing or bag
- more expensive than the others, but not much
- uses mini-USB for charging
3) Bluedio AV900 http://www.dealextreme.com/p/bluedio-av ... ndby-45575
Just got this one a few weeks ago as well. US $17.50.
- surprisingly good considering I got it from DealExtreme
- battery life is 5-6 hours so far
- good sound
- round barrel connector for charging
I also have a Motorola S-9, which I've never been particularly happy with. I cannot seem to get a comfortable fit and positioning, and it also seems to have more difficulty with interference and dropouts when used outside.