here my take on firewalls.
Most MNC i've met uses hardware based firewall as most of the hardware based firewalls are actually computers/servers which are easily upgradable. They can already match software based firewall interms of function and feature.
Most deciding factor is reducing latency in the network. You must remember that each packet that goes through the firewall must be administered thorugh the same process of checking/authenticate the packet and whether to allow or disallow based on its policy. this consumes time. Hardware based firewall reduces latency due to its opmimization factor. The software inside is optimized to run on that hardware and usually use BSD kernel as its base or something of that sort. Even some brands uses RISC processor to spped up the overall performance.

Software firewalls now seems to be sitting on client PCs most cases as it is not practical to put a hardware on every client.