looking for a general consensus here.  If I cast a minor illusion but leave the range of the spell, does the spell cancel or will the illusion stay until duration is expired

here is what the first line of the description states.

"You create a sound or an image of an object within range that lasts for the duration. The illusion also ends if you dismiss it as an action or cast this spell again."

I am under the opinion that it would/should stay up.

You are correct, the spell will remain even if you leave the casting range. 

Once a spell is cast, its effects aren't limited by its range, unless the spell's description says otherwise.

That's from Basic Rules, Chapter 10: Spellcasting.