It depends on the switch's architecture. I believe you could build a switch either using software or hardware alone, but as @MHM Cisco World wrote, it's generally a combination of both, although, again depending on the actual switch architecture, the balance is on a sliding scale.
As to which is "best" . . .
For "speed" you generally need dedicated hardware.
For "intelligence" you generally need software.
Also keep in mind, not only the balance between software and hardware can vary, but how "powerful" the software and/or hardware is, on individual switch architectures, also varies.
That said, the demarcation between software and hardware can be a bit blurred, as hardware might be supporting some complex function (internally to the hardware) using procedural steps, much like software instructions.
Perhaps the dividing line is whether there's any way to reprogram the hardware's operations via some form of instructions.
Of course, don't know how deep you want to get into switch architectures, but there's much that can differ when you really dig into the subject.
You only mention being a network student, so don't know how familiar you are with other computer systems, like personal computers, but consider when the IBM PC was released, its basic CPU (8088) didn't support complex mathematical operations, yet such functions were still supported, slowly, by software. However, if you added the numeric co-processor (8087), the computer would do some mathematical operations much, much (much) faster, in the co-processor's hardware.
Now a days, those earlier co-processor features are included in the main CPU, but when you get into graphics, for fast graphic generations (e.g. 3D games), you'll likely want to have a "graphical card", i.e. additional hardware.
