I've used an Opinel #6 as my apple eating knife for a few years now.
I lost my front teeth in a boating accident when I was younger, and have porcelain front teeth now. The only real change in my life, was that my dentist said never to eat an apple without cutting it up first. So I keep my opinel in my bag at work, because it slices great, and isn't scary to anyone.
I frequently eat apples slice by slice during meetings at work, and no one seems to bat an eye.
I've tried a few others, but so far the opinel has been the best for this that I've tried so far.