If you just want a mono headset with a low profile and good sound, I like the Motorola Elite Sliver. It's not the cheapest, but it works very well, has good sound and is hardly visible when wearing. I especially like the low profile and the mono for listening to podcasts while I'm out at the store or someplace around people where I don't really want both ears with buds in them.
If you want a stereo ear bud type headset for music, it's a little more difficult. I have tried the Motorola S10-HD which had decent sound and worked well, but they were tight and the manual doesn't say anything about the side bands being bendable, although someone had posted they did (gently) do this effectively. I had already returned them so I didn't try it.
The number one BT headset on Amazon is the LG Tone HBS-700 which I also own. They sound good, are extremely comfortable and would be perfect except for the fact that with my Droid Razr they default to a very soft, tinny sound which can only be remedied by pressing both volume buttons a few times to load a different EQ setting. I wouldn't mind that so much except that whenever I pause or stop the music, the music becomes soft & tinny again. As near as I can tell from both Amazon reviews and other forum threads, this is only a problem with the Droid Razr. I have used them with an iPod touch and there's no issue at all. So I've kept them just because I know of no other ear bud type that is as comfortable and they do sound good with the changed EQ.
I will be interested in what others experience is with this.
I have the Jawbone Icon and have been pleased with its performance both as a BT phone headset and also as an A2DP earpiece for listening to music, talk radio, and Navigation.
It is customizable from the desktop PC and also has an app called Jawbone Companion that allows additional control. It tells me when I have upcoming appointments, tells me the time, and more. The noise canceling is exceptional. By using a small rubber post which sits on your jawbone, it senses the vibration while you talk and by laying that waveform over the sounds coming from its two microphones it determines what is speech and can mask the background noise.
There's a cool demo on their website with a woman in room full of noisy kids and she talks both without and then with noise canceling on and the difference is incredible.
If you don't mind laying out a little more cash than the others go for, I would look at the Bose Bluetooth Headset Series 2. It comes for either right ear or left ear. I have purchased it and have used it since the beginning of January. I have had people tell me it sounds like I am on my house phone because of the noise canceling feature. It fits comfortably in the ear and at times, I have gotten home and had my wife remind me that I still have it in my ear.