If you mostly compose at home, get an iMac. No question. The 2019 is a beast at the moment and that 27" screen has no comparison. Yes, it’s 3k, but your MacBook will be almost at the same price at the end, after you upgraded RAM etc.
I still have my 2011 MacBook and if I think about what amazing things I still can do with it for actually 1250$ it’s awesome. The best scenario is to have both of course. Haha
If you compare power, screen etc. iMac.
If you still want to be flexible, get the smallest model, but i7 at least and buy an external screen for 150$, if you don’t have one already. I worked like this almost 7 years! It works too!