Why are you not researching enterprise level firewalls for an enterprise application? While many routers can do the job, they might not necessarily be the right tool for the job.
A bit more info on what you are trying to do might help. How are you defining "enterprise", would help...
What type(s) of WAN connection are you using?
What type(s) of LAN connection are you using or wanting to use?
How many connections are you looking to support?