Hello Aleksey,
It's late answer but since no one has answered your question I want to share something.
We used web dispatcher, F5 and Netscaler as load balancers in our SAP landscapes.
For F5 and web dispatcher comparison you can download a document from below link.
F5 BIG-IP and SAP Web Dispatcher - Considerations and Use Cases
Hope this helps.
Regards,
Yuksel AKCINAR