Distilled water is practically inert; no buffering, no oxygen, no nothing. It's this "nothingness" that makes it the #2 choice for reefers, after reverse osmosis water. If you go with distilled water you will need to add buffers and then aerate for at least 24 hours before adding to the tank.
The spring water would be best; check the hardness and if it's too hard then you can cut it with some distilled water. Although chlorine isn't an issue, make sure to use an additive like Start Right that will neutralize any heavy metals.