I bought a Simplisafe system and signed up for the monthly monitoring. After one too many false alarms thanks to my unruly cats, I decided to cancel the service; the customer service a-hole told me that if I canceled, it would immediately void my warranty. So, I canceled and got rid of it, chalking up the purchase to being unduly influenced by way too many podcasts.
I bought some Ring cameras on sale and set them up, and they work just fine - I don't really care about at-home monitoring since you can hear a pin drop in my place; if someone breaks into my house when I'm there, they will not enjoy the experience if I'm home.