I've used IOGear switches for at least 10 years (GCS1102 and work and GCS1104 at home). They're pricey but full featured, work seamlessly, well made and durable.
The GCS1102 / 1104 (2 versus 4 computers) is the cheaper option, but only supports resolutions up to 1920x1200.
The GCS1784 is the more expensive version that supports 3840x2400 res.