Hi,
I feed my big beardies finely chopped rainbow chard from my yard. It all tastes the same to m. It comes in pink, yellow, magenta, plain, red. I also offer finely chopped or sliced zucchini, butternut squash and some other green - like collards or mustard greens. a few silkworms might be placed on top (they tend to stay put all day). i don't mix it and let them choose from the separated portions. Sometimes they eat all of one pile and not of another. Over several days, it balances out. One beardie's fav is sliced zucchini, the others is any type or green and the butternut squash. the iguana loves chard, but also likes collards and other greens. i don't think the color makes any difference since all are doing great.