The ability to go back and look at historical data is the most valuable feature. 

Memory and CPU utilization features are good. 

There are so many features. One of the most valuable features is the ability to alert, proactively, on a variety of issues on which we would normally not get a heads-up, that something is going to happen. The alerting functionality is important.

There are a few pre-designed reports that we use for database and disk usage growth, that allow us to show, over time, how much a database and disk space have grown. They help us plan for the coming year.

The most valuable features are disk space projections for planning, and also the Snapshotting ability, to look back in time, to see what was going on the server at a particular time. It's basically the output of an sp_who2.

The best part of SQL DM is the ability to customize alerts and counters. This allows our team to find an issue, then alert on the issue at a granular level.

I love the customization of the alerts.

We created several stored procedures/functions that would query multiple DMV’s and alert if a certain threshold was reached. However, since new DMV’s are added, or older ones are adjusted, it caused too much headache to continue to support the home brew method.

The capability to baseline the environment and define thresholds for alerting is definitely the most valuable feature in my opinion. As an operational DBA, I don't write code but need to make sure the SQL servers are healthy, performing scheduled jobs and made aware when issues arise.

Ability to identify bottlenecks, deadlocks and slow running queries and run monthly and daily reports.