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.

Top 1 for 1080p 4 port USB 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 for 1080p 4 port USB VGA KVM Switch

Can you see this model looks like the above? I doubt it's same supplier.

Top 1 for 4K 4 port USB HDMI KVM Switch

Pros:

I really like this one. In fact I have one for my 4 computers. it's 4k 30Hz 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 monitor as the 2in1 cables are 5ft long, but good working by now.

Top 1 for 4K 4 port USB HDMI KVM Switch

Pros: This KVM switch is suppled by Tesmart. it's 4K 60Hz KVM, price is higher but worthy if all your computers and monitor support 4K 60Hz. Cons: If not all your devices support 4K 60Hz, this one may drop off the resolution for all devices like computers, game console, and monitor.