what is the best pencil to use with my new iPad 10th generation?

You can use either the First Generation Apple Pencil or the new USB-C Pencil.

Both will work with it fine.

The Second Generation Apple Pencil will not work with it though.

The First Gen and USB pencils won't offer any differences in features though outside of the Magnetic attachment option available on the USB-C Pencil. Its just comes down to which one you like more.

the first generation of the ones apple makes is the only one that would work with it

Apple Pencil - Apple

you can also use any old

Amazon.com : capacitive stylus

it would likely be the cheaper option