I've been using "StarTech" brand for a 2 way KVM VGA and am highly satisfied with it.  I run 2 Dell 27" monitors with 2 main PCs.  VGA works fine to the 1440x1200 Monitor limit.  With DVI you can get higher resolution per monitor.  I've had that KVM for the last 6 years

I've been looking at acquiring a 4 way KVM with DVI-USB as well for the same purpose and the StarTech will be my first choice. 

Note that as soon as you introduce VGA into the cabling you will be reducing the resolution of the monitors, as VGA has lower limits in spite of the DVI-VGA convertors.