Some will start arguing that standover height is a worthless measurement. "You don't stand over your bike, you ride it." I am not one of those. I stand over my bike at a variety of traffic lights, drinking water, fidgeting with zippers, gloves, etc...a bike I can comfortably straddle is not superfluous.

In theory, a bike that will always be on a prepared surface needs 1" of clearance. A bike that will encounter mild chop 2"-3", and a bike that will no kidding be off road needs greater than 3". How do you determine clearance? That is actually more subjective. Some determine that height by measuring the height of a rigid object (say, a book) that is pulled up to FIRM contact with your pubic bone. Others go the opposite extreme and measure to just touching the boys. Me? I measure to firm contact, but not uncomfortable...i.e. I don't pull as hard as I can.

A quick way when checking a bike is to pull the top tube up to full contact and measure how far the front wheel is off the ground. This has some "fudge" to it due to sloping top tubes, and where you happen to pull this time, but it can get kinda close.

A hybrid, by the by, is typically little more than a hardtail MTB frame made road friendly. Have you considered possibly getting an adjustable stem, and simply moving it based on what you want to do that day?