Basement door, if you have a furnace down there, you may want to replace that cheap hollow core, with a door, that has a longer burn time, just in case something does happen. Plus side, a solid core door will not ding so easy. If all of your doors are standard sized doors, I would definitely look at replacing them with solid core doors, so they can stand up to the abuse that kids can put on them.
Plus side is, they would add resale value to your place if you ever decide to sell later on.