Apple Pencil has a nice ceramic tip with several small bits of metal in it, this gives it a good handle on tilt sensitivity. The ceramic tip will break if you drop it on a hard floor like concrete. The tips can be replaced cheaply. The charging is by plug in to the only port o the iPad. You can't change the battery and need to replace the pencil if the battery starts to go. No buttons, and no eraser function on the back.

Surface Pen has a plastic tip and can also be replaced. I think you could break the tip, but you would have to try pretty hard. There is battery which is removable and hence can be replaced and does not need to be charged. This stylus also has button functions and an eraser on the back. You can do nifty things like have it open a program with a click and even switch back and forth between 2 programs with a single and double click. I am still playing around with the possibilities for the buttons.