Incident.io is likely our closest competitor and are doing amazing work over there. They have a strong team and smart founders that have been in the trenches before. From a product perspective they are my favourite of our competitors if I had to pick one myself to use.
Our differences are largely driven by the customer segment we serve and the needs of SMB vs. enterprise. We've found by going upmarket to enterprises such as Canva, Shell, Bolt, it is quite difficult to develop an opinionated platform based on only industry best practices as each organizations approach to incidents (regardless if it's the same tooling) vary greatly in their process. You'll find Rootly to be a lot more pluggable, customizable, and can turn any knob the make the product work for you if needed. The reason for this is because we find change is hard, even small process tweaks in process. We want to reduce as much of that as possible when a new tool is brought in.
We've been around longer so naturally our product maturity is further along. Such as Workflows (https://rootly.com/changelog/2021-11-30-workflows-2-0), integrations (30+), Terraform/Pulumi provider, and security (https://rootly.com/security).
Again, they do a great job. Just different needs and requirements for startups vs. enterprise.
If helpful, customers have written reviews for us on our respective G2 pages: https://www.g2.com/products/rootly-manage-incidents-on-slack...