Application of wax/sealant isn't particularly difficult, but it can certainly wear out your fingers if you don't have the right pad. I prefer to put my protection product, or last step, on by hand rather than by machine to reduce any chance of marring the surface. These are the pads I've been using for about 5 years now.
I'm pretty sure I've bought and tried every applicator pad in existence: foam, microfiber, cotton, large, small, etc. These are my favorite by a mile. They are just pliable enough to get into curves and tight spots, but the stiffness of the handle reduces fatigue. I've tried to cheap out and buy some knock-off, but they always end up being too stiff.
I use the Yellow for Sealant and the Red for Wax. These can be used and reused dozens of times, so don't let the cost scare you away. Buy a few of each, and they will last you a few years.