I love greens and I think Kale greens are great!! I also grow a LOT of beets each year just so I can harvest and eat the beet tops for greens. I also eat Mustard and Turnip greens along with a host of edible wild greens like Nettle, Purslane, Lamb's Quarter, Garlic Mustard, Dandelion, Poke, Broadleaf Dock, Plantain, Galinsoga, (quickweed) and others.

The wild greens are much higher in essential vitamins and minerals because they evolved as plants that can extract from the soil the nutrients they need without the benefit of commercial fertilizers.

Side note...
Purslane is higher in Omega 3's per serving than wild caught Salmon and it grows in my garden every year!!! Ya can't beat weeds for nutrition if you know what to look for!

BPS