The Logitech C920/C922/C930 series with autofocus are OK for personal or small group use. Of the consumer USB webcams, I haven't found any other makers' to be as good. Only 1080p 30Hz, but any more is demanding too much of your recipients' bandwidth and hardware in the general case.
Advice from my wife, a photographer:
- if you're still having picture problems (after setting the camera's anti-flicker to 50Hz/60Hz as appropriate), put diffuse illumination on your face e.g. a full-screen browser window on http://blank.org; or for more control--colour temperature as well as brightness--a cheap LED panel and desktop tripod (from a photo supplies shop).
- turn off any "smoothing" or "beauty"features in the cam's software.
- likewise, don't use any fake background features. Pin up a plain bedsheet behind yourself if you think your place is too messy to be the background.
Anyway, once there is a picture of any kind, in my experience most people care more about the audio being unclear or laggy, so you're well ahead.