Whatever camera you end up going with getting in and messing around with the settings is a really good idea too (as well as what Audri said about lighting). The logitechs are a great choice. I went with them for many years.
For those download the logitune software as well as the logicapture software. That way you can change up settings. Depending on light and time of day, ideal settings change. The one thing I always go in and do, is crank up the sharpness a bit. If you're really focused on clarity and have a visual preference for more detail, this makes a huge difference. The default settings on Logitech are not ideal, in my experience. I am pretty anal though, at least with that. You can also disable autofus in those softwares too.
Physically moving the camera is usually going to be better than zoom features with most of these cameras. Because a lot of time clarity is lost if you use a zoom feature. I think on some more expensive cameras it's not, but who has thousands of dollars to spare for that.