Both. Headphones are great for catching small hidden details, issues. 💯

I produce and do basic compression panning and EQ then mix in headphones

I make my music in headphones then mix on speakers. I still go back to headphones now in then when mixing just to see if what I have still sounds good on both

Mixing on headphones is rubbish unless necessary, ie travelling or at night if you have thin walls

I mix on speakers but check my work on various headphones as I go. Mostly to see how it sounds in different listening devices and what I think of it

Mixing on calibrated speakers in a treated room is ideal and preferable to headphones imo, but in practice I work at night and use headphones more often. Good headphones can be better for catching high end details, and there’s de-binauralyzer plugins to workaround the stereo issues.

Using Steven Slate VSX to mix. I use a room that has NS10s since I’m used to those monitors.

I’m sure a lot of folks have already said, but a bit of both is always useful! I like to mix on speakers and check in headphones that I’m familiar with to check certain frequency areas. (And honestly, I always check on AirPods at somepoint since it’s a popular medium!)

Both 💪 Speakers overall picture. Headphones details

Both, switch often.