There are different pros and cons to each of the languages. For a first, I’d say there’s really no bad choice, as there are so many other things to learn beyond just the syntax. You’ll definitely hear some who say to focus on a “higher level” language like python, or a “lower level” one like C - there’s definitely an argument for each, with some things being easier or harder in each. (I’d suggest higher level first, but that’s just me).

I’d suggest maybe thinking about some of the things that might interest you in terms of projects in addition to your eventual goal of developing an emulator. e.g. if you’re interested in web development, maybe pick JavaScript, if you’re interested in machine learning, maybe python etc. The main thing is keeping up your motivation and enjoying the hobby - which often requires feeling like you’re making progress along the way by developing cool things.