Chrome and Firefox both fallback to forms based auth after failing SSO with Kerberos at Netscaler. IE works fine.

Add Chrome and Firefox user agents using the Set-AdfsProperties -WIASupportedUserAgents command at ADFS. 

Example:
Set-AdfsProperties -WIASupportedUserAgents ("MSIE 6.0", "MSIE 7.0", "MSIE 8.0", "MSIE 9.0", "MSIE 10.0", "Trident/7.0", "MSIPC", "Windows Rights Management Client", "Firefox/25.0", "Mozilla/4.0", "Mozilla/5.0")

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Problem Cause

The issue is that ADFS does not allow all browsers to do Integrated Windows Authentication by default.

You can check the supported user agent types by using the following powershell command:
Get-AdfsProperties | select -ExtendedProperty WIASupportedUserAgents