The Designer Two Story is a good choice; a lot of people go for that. Personally I skipped it and aimed for the Riverside Mansion because I didn't like that it had the same number of pumpkin slots as the Woodland Bungalow. But that was before we got the Renovated Farmhouse, which has a whopping 6 pumpkin slots (and I see somebody selling one right now, if you're interested). I guess it depends on the player. What would you like to have more of? If you're going to move into a significantly bigger house, I wouldn't worry about fully furnishing it at first. Having an empty house is unavoidable for a little while, and your decoration collection will build up naturally as you hoard.

I'm going to buy the urban villa tomorrow, I just need to empty my current one.