The only experience I have with Juniper is some of our business partners use Juniper on the remote end of an IPSec tunnel.
So what I can tell you is a bit limited.
I believe Juniper may not allow multiple prefixes to be grouped into one security policy.
The defaults are different -- and sometimes we had to go 'less secure' to ensure compatibility.
I could be wrong but I believe TACACS+ is still proprietary to Cisco.
So is EIGRP.
Other than that, there's the obvious differences when configuring.
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As far as making it harder on hackers...
With my experience, I'll go with Cisco every time. For consistency, high availability, and because it's what I know.
If I were just as familiar with Juniper I'm sure I could make a secure environment with Juniper devices.
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I don't think I'd ever mix and match willingly, for any reason.
