Fresh water. The salt slows down how fast the ice melts (I'm not sure why).
If you still really want to know, do an experiment. Put different amounts of salt into a cups of water, and leave one without salt. Put in some ice cubes and if you want, use a stopwatch to see which how long it takes for them all to melt.
If you still really want to know, do an experiment. Put different amounts of salt into a cups of water, and leave one without salt. Put in some ice cubes and if you want, use a stopwatch to see which how long it takes for them all to melt.