I find that Rainier cherries or dark sweet cherries work best in this recipe as they are naturally sweeter. Both of these are generally available at your local grocery store. I usually use half and half or you can use all of Rainer or dark sweet cherries if you prefer. You can use sour cherries as well. If using sour cherries or tart cherries, you will need to adjust the amount of sugar. I’d recommend starting about 1/2 cup and working your way up if more sweetness is needed.