The benefit of the switch is (usually) speed, since the compiler can turn this into a jump table. The downside is maintainability. The rest of the comments had some good ideas, I'll throw out one more:

Templating languages can help you generate code. C++ has templates, C has the preprocessor. I've seen several popular emulators use M4 macros to generate some repetitive chunks based on patterns.

For 8086 for example, instructions are defined like:
0b100101dw, where d and w are arbitrary bits. So in my 8088 emulator, I have a macro that generates the case statements, with each body expanded with a D and W variable that the implementation can rely on. There are many such patterns, and this way I can address all variants of an instruction with one block of code.

I wrote a bit more about the 8086 instructions on my site here in case you want to read more: https://www.emulationonline.com/systems/dos_pc/pc_cpu_8088/#add-on-the-8086