I think cashew or even almonds could be good. There is also Kale. I had made a Kale shake that I thought was pretty good.
I used Kale, spinach, almonds, brazil nuts, some sun flower seeds, pumpkin seeds, just a little bit, some pre soaked chia seeds. Some lemon or lime. Blend with a bit of water and pink Himalayan salt and pour in a glass, and to top it off add some fresh chopped onion, and cilantro. Stir it up and there you have it.
It sounds weird but it is pretty good though. The nuts blend down and you barely even notice they are in there. It gives it a good flavor. I ate that invention a few times. It was alright. I think that in your drink cashews could be a good complimentary flavor. Maybe even macadamia.