As already clear, the option with a mortgage is more preferable, since the rental of an apartment is certainly good, but in this case it is not property, which means limited possibilities regarding the repair and much more. Everything will have to be repaired for their money, and in addition, there is always the possibility that the owners of the apartment at one point will notify that new owners will be populated in it, so it will have to leave it. As for the apartment taken in a mortgage, then there is a risk of its loss for non -payment, but this is already another story, there are much more pluses here.