The short answer
Recommended headset
This is the one we recommend first. It is the clean option for Webex on a computer, and it can also work with a Poly desk phone when you add the EHS cable.
Poly Savi 8210 Office
Buy this when call quality matters or the user may also use a Poly desk phone.
Best for: Webex on a computer, or Webex plus a Poly desk phone when you add the EHS cable.
For computer-only use, buy the headset only. For Poly desk-phone call control, buy the APP-51 EHS cable too.
Bluetooth headsets
Use Bluetooth when you want a smaller, more economical headset. Newer Poly Edge phones support Bluetooth, so they can technically use many Bluetooth headsets.
Poly Voyager 5200
Buy this when you want a smaller Bluetooth headset, especially with a newer Poly Edge phone.
Best for: Poly Edge phones with built-in Bluetooth, mobile use, or a computer where Bluetooth quality is acceptable.
Computer Bluetooth quality depends on the computer chipset and is not fully in our control. For phone-only use on a newer Edge phone, it should be fine.
A note about Bluetooth
Bluetooth headsets can work well, but computer audio quality depends a lot on the Bluetooth chip and drivers in the computer. If the user needs the most reliable computer headset experience, buy the Savi option above. If the user is mainly using a newer Poly Edge phone, the Voyager 5200 or another Bluetooth headset should be fine.