If you’re thinking that you might be in a arroyo and need help, a PLB is more likely to get its signal out than an InReach or a SPOT. The PLB will have an as-good or (usually) better antenna, with more transmit wattage.

Essentially, a PLB is less flexible (can be used only once, and only for an emergency signal) but has more transmit power and is therefore more likely to cause a rescue to be launched if the transmission conditions are poor.

The private-sector rescue coordination center used by SPOT and InReach (Geos) is now owned by Garmin as AKSAR noted. I don’t know anything negative about them. The USAF and USCG rescue coordination centers work hard to be the best in the world at what they do, and undoubtedly have more practice.

Whatever device you have, register it, and make sure to file a trip plan with a responsible person that the RCC can reach.