high latency means you have a good connection, low latency means you have a baad connection

A transcontinental fiber link might have many gigabits/sec of bandwidth , but the latency will also be high due to the speed of light propagation over thousands of KM.

In constract a 56 kbps modem calling a computer in the same building has low bandwidth and low latency

Latency is defined as the network speed in which the information being broadcast from the original server reaches the individual's device by measurement of milliseconds. This means that a lower latency will allow more information to be sent or received and thus, creating a better experience. Improving low network latency can be accomplished by establishing more latency-sensitive software so that multiple tasks and improved performance can occur.

Improved security makes sense, but actually Cisco says " Keeping the network diameter low ensures low and predictable latency between devices."

So I'd go with lower latency

I don't think this is the right place for this kind of question.

The interrupt latency highly depends on the MCU. It could be as low as 10ns or as high as 100us.