I use a combination of both, but that's just to get the right mouthfeel and taste. I use coconut milk from the cans, as the boxed stuff has a lot of crap added to it and it's watered down. Same goes for the Almond milk, but it isn't offered in the same way. Ideally, if you had the patience, making your own almond milk would be the best.
But as far as nutritional advantages are concerned... Almond milk has more minerals like magnesium etc. Coconut milk has better fat IMO. I prefer saturated fats like capryllic acid, especially for the MCT's. But again, mixing them together is my favorite.
I usually take 2 parts almond milk to 1 part coconut milk and 1 part yoghurt(usually Greek or Kefir). Throw in fruit if I'm feeling it, greens powder and some protein. Incredibly satisfying and nutritionally dense while low in carbohydrate (if you go easy on the fruit).