which collet stud remover tool do I need?

[pmax]

Costly, cheap, cheaper ...

https://store.snapon.com/SearchResults.aspx?q=Cg500&IsPartsSearch=0&departmentName=Tool%20Catalog[/QUOTE]
$166

https://www.amazon.com/gp/product/B00265M8N4/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1
$22

My $14 head stud removal tool that kicked a**....
$14

Time for a head to head test ?

[KTL]

The inexpensive ones are great for broken studs. They grab on like a vise and dig into the metal. The expensive Snap On collet setup is of course threaded, so you need various collets for different thread sizes, and the tapered body & collet assembly clamps onto the threads when you cinch the body tight.

So basically the Snap On collet thing only works if you have threads. Works great for preserving threads if you are removing and reinstalling the studs. I use the M8 collet all the time when i'm cleaning up cam housings.