I don't know if this is true or not, but I was told that canned vegetables lose their nutrients, where frozen can be just as good (nutritious-wise) as fresh.
I prefer frozen over fresh or canned, just because it might be awhile before anyone in my household will eat veggies. Fresh veggies always spoil too quick on me!!
Mamu, I always steam the frozen veggies, so as not to be too soggy or mushy. They always come out great!