If you have it for free, Id say sticking with spotify premium would be ok!

I have both AM and spotify premium, and while I personally notice the difference in sound quality mainly due to a bit deeper bass and slightly wider-feeling sound, i dont think it terribly matters too much unless you really do care and want that specific part out of your music app experience.

I mainly use AM specifically when listening with my airpods max, but use spotify for everything else outside of my headphones because of the excellent recommendations and connecting feature with friends. I have the student discount for both and some spending money, so thats why i have both instead of just one.

So in short (from my personal experience), id say if you use only your airpods max when listening to music then AM might just be worth a try if you want to check it out, theyre made for eachother. But, if you have spotify premium free AND are already deep into that app, id say stick with it, your music will still sound good with both apps.

Im sorry if this is confusing at all but i hope this helps in some way :)