I needed to protect the sproket on my 2020 EXC so I've looked at a few of these things,
I chose the Acerbis one because I liked the design feature where the section of the underside is removable. This allows simple and easy installation and removal for maintenance and it is a replaceable part which can be purchased separately when it becomes worn or damaged.
Clear installation instructions in case you don't use YouTube for everything you do on the bike.
This is a pretty solid bit of kit manufactured from very robust material so I am expecting good lifecycle from it. The majority of competitors products are more expensive that the Acerbis product and as far as I can see there are no features they offer above this one.
If you have a dirtbike and it doesn't have a chain guard get one of these