I usually use a peeler/corer/slicer when doing 5 gallon buckets of them to make pear sauce and apple sauce, for canning. I use it for baking or just eating.
The slicer can be removed on some of these contraptions. I use it for canning for potatoes.
If you're going to end up slicing or dicing the apples, Just peel and quarter them the you can easily cut out the core with a paring knife. You could also use an apple corer.
I haven't used my melon baller for melon yet. I have had it a few years. I have used for coring apples and pears. Yes, with the pears I use a knife to remove the strings.