Fresh over frozen! – and -Frozen over canned!
Fresh ingredients are far more nutritient rich than their frozen or canned counterparts. And frozen produce is more likely to have been processed in a fresher state than your canned produce. Canned is the last on the list because the nutrients have been given the most time to decay and breakdown. Also it has been soaking for a LONG time – allowing most of what is good in the veggies to seep out into that liquid your going to dump down the drain when you open the can.