Top 1:  4 port USB VGA KVM Switch

As for 4 port USB KVM switches, not many are available on amazon. Naturally, we don't have more choices. We have to keep an eye on the new ones.
4 port VGA kvm switch
 

Pros:

This one includes 4 2in1 VG KVM cables, and built with one additional USB hub for U disk, printer or USB speaker. it's the best one.

Unlike the old version, only 4 VGA 2in1 cables, your desk is not messy.

Cons:

I don't think 4 5ft cables are long enough to reach all computers. The good thing is that 10ft are available to buy

 Top 2:  2 port USB VGA KVM Switch

 
dual port kvm switch 2 port kvm switches
 I owned 2 pcs this models, it's good working. By now, it's 8 months and no any problem.

Top 3:  4 port USB HDMI KVM Switch

4 port kvm switch 4 port kvm selector
 Pros:

I really like this one. In fact I have one for my 4 computers. it's 4k 30Hz, up to 3840*2160 resolution, and built with USB hub for my USB speaker. My previous model was not the 2in1 version, so I had to plug 8 cables with computers and the switch. it also includes a wired desktop controller.

Cons:

The cable length is always an issues for me. I have to move all computer close to my