The only problem with both MS castles is that the outside is the biggest part. The inside of both is quite small. But, obviously, the more expensive one is better. If I were you, I would save up to buy a house from the crown shop with gold.Hope this helped!
Well if you want my opinion, I think the one house your going to stick with the longest. Some people that have memberships actually have enough gold to buy two houses at one time, but if your not your really tied. If you buy the small house and you're not happy with it whats the point, but it's not good to spend too much gold either! Big house it is!
It also depends on what you want to do with the houses. For me I'm getting the smaller sized Mooshu house simply because I don't have that many items to decorate it with. I also do not garden so I don't need the plot space. The small sized house is really nice, and easily workable with the amount of space.
I like my small MooShu house, it's my second home and I didn't want to have all those rooms to decorate. I love decorating the exterior most and it's a beautiful garden for my dragons to fly around and play in. Plus I love the little underground room. It was the perfect choice for me.