Evaluating the SRX series vs McAfee Enterprise Firewall and Palo Alto NextGen Firewalls. Is there a comprehensive list of the apps that are in the AppID database? Is the list updated regularly? How do the three implementations compare? Is there anything we loose in terms of capabilities if we end up with a non-Juniper firewall but with other Juniper gear (EX, SA / MAG)?
For comparison, you should do more than look at the list of apps though, see how the different vendors apply their application identification. A basic url or a port-based lookup will be less accurate than something that involves an application signature. Also look at whether you can customize existing applications, view application signature details, and create your own application signatures. Also look at the logging and reporting capability - the AppID logs via SYSLOG are detailed and well constructed.
A few unique things from your list that you might get with a Juniper FW and other Juniper Products are one Pulse Client for Dynamic VPN to SRX and MAG. Possibly the IPS/MAG integration if this is on the Roadmap (the capability exists in the Juniper IDP product range). Also if VGW is in your future for your Virtualized Environment then VGW/SRX integration might be of interest.