These two completely different terrains to compare. Both are extremely beautiful in their ways. Ladakh is mostly naked very high mountains with less of water while Meghalaya is mid high vegetation full mountains with abundunce of water. Its perfectly your what you want to experience.
Every place has it's pros and cons. Likewise for Meghalaya or Ladakh. The most important being the scenery. We cannot compare apples to oranges hence comparing a Ladakh to Meghalaya is unfair. Ladakh is dotted with high himalays and barren cold deserts and beautiful night skies giving a different type of experience while Meghalaya is dotted with lush valleys, verdant greens, magestic waterfalls and more or less a lot less explored hence the element of adventure is always there. You should plan a visit to each place at a convenient time. I'm sure they both have something to offer as lifetime memories for you to cherish.