Personally, First Alert is the only company I trust for residential smoke alarms. These are life safety devices, meant to keep you alive in the event of an emergency. I personally installed the First Alert SMCO100V-AC alarms in my home after the Siterwell versions put in by our builder malfunctioned. Kidde has had plenty of recalls over the years, and companies like X-Sense are too new to make me comfortable.
Recently, X-Sense alarms were pulled off Amazon (they are since back) because they did not have up to date UL217 testing. They were tested with an older version only at the time. The thing is that the requirement was clear for a while before the listings were pulled. A company worth it’s salt should be trying to ensure they are compliant with latest UL standards as soon as possible, and X-Sense failed to do that. While I’m happy they have corrected the matter, it shouldn’t have been an issue in the first place.