I prefer using tools and converters that let you convert files as you download them rather than converting already downloaded files. Hope my attempts to explain make sense... Anyway, I've tried tons of different converters and went through a lot of free online ones that ruin audio quality to tools like pulltube, which I read about on setapp https://setapp.com/how-to/convert-youtube-to-mp3. It lets me choose the audio file format as I download it. I think that's the simplest and most convenient option, without any extra steps.