Helicopters - What makes a "good" helicopter?

[MathHelp]

Hi team,

I was wondering how to determine whether a helicopter is good. As an example, with an Army tank, you would judge it on the criteria of protection, firepower, sensors, and mobility. Are there specific things that you can look at to determine that a particular type of helicopter is going to be "better" than others?

I am mostly thinking in a military context.

I am particularly interested in comparisons between a Blackhawk/NH-90/Mi8 helicopter.