OMSA + ISM + iDRAC + VMware

Question

All of our old servers used OMSA for management because we didn't have iDRACs available. With our new servers, they all have iDRAC Enterprise cards and 90% of those are running VMware ESXi. I'm trying to see what OMSA will provide over top iDRAC for monitoring and alerting. I understand that the ISM will expose certain OS characteristics to iDRAC but will OMSA provide anything above iDRAC? Also, since these are primarily ESXi hosts, is there even a need for the ISM? Has anyone put together a chart that details the level of features provided for each method (OMSA, iDRAC, with or without ISM, etc)? We also have two use cases for receiving alerts and monitoring. Our main IT group is leveraging OME (current essentials but quickly migrating to enterprise because it's a million times better) and another project is going to just have SNMP alerts being sent to another system. I told them initially that they should use iDRAC for this but they inquired about OMSA. Finally - with ESXi having knowledge of hardware - should we ideally scrap OMSA/iDRAC alerting and just use vCenter because we get alerts on VMs AND it knows about hardware failures. There seems to be too many options right now and finding the right one for the job is a little confusing at times.