I use to eat frozen broccoli and let me tell you they must lightly mist it with feces because it will make you gag. I'm not sure if it makes it less nutritional or anything to buy it frozen, they say something like if it's flash-frozen the nutritional value stays the same but i don't know because that stuff tastes horrible if it's frozen. Frozen veggies are about as comfortable to consume as hot beer.
Fresh is the best way! Frozen, canned, and steamed the veggies become dehydrated and they lose their nutrients and potency. And I agree with Still Life, I can't eat frozen Broccoli. I thought I was the only one who gagged. I'll eat fresh anytime
Go with frozen over canned veggies everytime. Frozen veggies are picked and frozen quickly, retaining most of the nutrients as opposed to canned veggies which are picked and later cooked at some plant with a ton of sodium. The texture of frozen veggies is much better than the mushy-ass canned veggies. Also, in some cases frozen veggies retain more nutrients than fresh veggies due to the amount of time veggies are on the shelf and how long they were in transport.