Another vote for the Motorola headsets, just replaced my year and a half old HS850 (picked it up for £50 back then, should be easy to pick it up for around £36) with the newer H700 (£44 when I ordered it last week) and both are fantastic. The good thing with these two Moto headsets are that they don't need to be worn at all times. Got an incoming call? Simply flip open the mic and after about 5 seconds, you are connected.
They are both light and comfy but that depends on different users. Battery life is fantastic compared to the Sony Ericsson headsets I've used in the past. The HS850 can be described as durable, I've dropped it many times (in heavy rain too) and it still works fine. The rubber part which blocks out unwanted sound from the speaker started to wear out on mine, hence the replacement.
I've also had no problems with Bluetooth when pairing these headsets with the various handsets I've used.
[EDIT] Carphone Warehouse is selling the HS850 for a ridiculously cheap £25 online![/EDIT]