We had an AngelCare with our oldest (he's now 4.5) and went with a SnuzaGo for DS2.
I much preferred the SnuzaGo. The only real reason was that it was more portable and we travel a lot. We had to stop using the Go around 7.5 months because DS2 is such a wiggly sleeper and sleeps on his belly so it was dislodging from his diaper and giving too many false alarms. We even tried a tighter onesie over it in hopes that would keep it in place better but it didn't.
We stopped using the AngelCare about the same time with DS1 but not because of false alarms. We moved to Europe and couldn't use it with their electrical system. We acutally used the sound only portion of the AngelCare for quite awhile after we moved back to the US.