Office 365 Monitoring.

Hey Team, 

We are in the market for an Office 365 Monitoring solution. Our tenant is pretty large at about 25K mailboxes, all E3 licenses. 

I have found a few different ones to pick from that look pretty good to me, but i am curious what enterprise office 365 specific monitoring solutions you all are using? 

We are looking for at least: 

1) Up/Down monitoring 

2) Service Health Functionality Monitoring

3) Covers all the primary workloads and security and compliance where applicable. 

4) Other items we might not be thinking about but that would be good. 

5) Ideally with no on prem agents, but i realize some features may require that. 

6) Not looking for any type of management solution, even if it also provides monitoring. We would like a dedicated monitoring solution. 

Cost is always a concern, but for now lets just set that aside. Please note we are aware of the built in options, 3rd party code, splunk etc. But we would like a full featured enterprise monitoring solution. 

Hey TonyRedmond or VasilMichev - MIght you guys have some insight on this? Sorry to bug, but if either one of you could point me in the right direction.....TIA

Thanks, 

Robert