The caviates here are a finite time horizon, whether or not you ever plan on selling your house and whether or not you care about what sort of inheritance you want to leave. If person #1 and #2 both live in their houses until they die and don't have anybody they want to leave their money to then it depends on how many years there are between #2 pays off his loan and when he dies (since from your perspective all your loans are cancelled when you die)