I’ve used both. I had a spot for years but recently (in Canada) the subscription costs got high. Almost as high as subscribing to an inreach mini (once you’ve brought the device).
The spot is great as last resort or if you are doing very long trips. Things I didn’t like about the spot.
1) Limited options for messages.
2) No real confirmation message gone through.
3) No communication (nature of problem etc) in case of emergency.
The inreach mini solves all of those but you do need to remember to charge it. Garmin also uses iridium network so more coverage than Globalstar.
Much like the above when I cancelled my spot they tried to keep me by cutting subscription costs a lot but I’d already brought the inreach…