I have to chop one tonight for a casserole. I don't enjoy the chopping but the flavor and texture of a fresh onion IMO makes a difference in a dish.
I will say I have never tried the store chopped frozen. I do however chop them myself to avoid waste. I do this with onions, peppers and celery. Those are used for flavor in soups and stews but not in things that need that fresh crisp items like tuna, chicken, potato salads and omelets.