It depends what the F5 or NetScaler will do.
You can use any load balancer in the front of the ADFS servers or WAP servers. As long as:
- they support SNI for inbound connections
- they support SNI for the health probes (else you'll have to configure some custom bindings)
- don't break the SSL tunnel between the WAP servers and ADFS servers
- don't break the SSL tunnel between the client and the ADFS farm if you use certificate based authentication
- capable of showing the real IP of the client to the WAP servers and ADFS servers (else it will only show the IP of the load balancer in the logs).
Now, if you plan to use F5 or NetScaler as a replacement for WAP (ADFS Proxy), then we have guidance. A third party ADFS Proxy can supported as long as it stick the the following specifications: MS-ADFSPIP: Active Directory Federation Services and Proxy Integration Protocol. As of today, only Big F5 did the work and can be a full replacement of WAP (with no loss of a security nor features). AFAIK, NetScaler did not.