Hey!!
both places are amazing, if you are nature valley lover , then meghalaya could a better option , or if you want some adventure then go for leh ladakh.
I think this is like comparing apples with oranges. It really depends on what you are willing to experience. Lush greenery, beautiful forests, go for Meghalaya. Stark, almost surreal landscape - certainly Ladakh. Weather wise, Ladakh will be much cooler. And lastly, I found the local food to be wow in both the places.