What Apple Pencil I can use with iPad 5th gen?

None. The fifth generation iPad does not support either of the Apple Pencils.

You can use 3rd party styluses however. Adonit is highly recommended around here: https://www.adonit.net/

If, you do not wish to wait for Adonit to restock its very good Adonit Pixel stylus, you could get by with a much cheaper, easy to obtain, commonplace, clear “disc tip” capacitive stylus that are easy to find on Amazon.

These commonplace stylii offer no screen pressure sensitivity to do light/dark/thin/thick lines and no palm rejection.

To lay your palm on the screen, you need to purchase and use a special, non-body, electrical conducting, lycra-based material drawing glove that works by isolating the electrical signals from your hand/palm and allow you to lay your hand/palm on the screen as you draw or write.

Something like this found on Amazon.

https://www.amazon.com/Professional-Anti-fouling-Drawing-Tablet-Graphic-Right-Ha nd-Left-Hand/dp/B017R8M2JY/ref=sr_1_1_sspa?ie=UTF8&qid=1543548123&sr=8-1-spons&k eywords=lycra+drawing+gloves&psc=1

Many more makers of these types of gloves found on Amazon and in different hand sizes.

Again, if you do not wish to wait, this is the only other cheapest way to get writing or drawing on your model iPad.

Best of Luck to You!

None.

The 5th gen iPad lacks the necessary screen hardware inside to support any version od the Apple Pencil.

Sorry.

I, usually, recommend the Adonit Pixel stylus for any non-Apple Pencil compatible iPads, but, currently, both Adonit and Amazon are out of stock of these.

This is really THE ONLY smart, Bluetooth stylus that truly works well enough on non-Apple Pencil compatible iPads.

The Adonit Pixel stylus is compatible with ONLY about 2 dozen, or so, of the more popular drawing and notes apps.

There is really NO other real good alternatives out there.

Wacom, the tech leader in graphics tablets and tablet stylii DOES make a smart, Bluetooth stylus for Apple, but ironically, it is a very bad and horrible stylus experience on iPad and doesn't even work well with Wacom’s own iOS and compatible stylus app, Wacom Bamboo Paper sketch/drawing app!

Stay far away from Wacom stylii.

I contacted Adonit directly, myself to get more information on the restocking status of the stylus, and they have indicated to me that more of these Pixel stylii will not be available until end of January 2020 or early February 2020.

Basically, around a month, or so, wait for Adonit to restock these.