hi there, did you make a decision yet? if not, i might be able to offer some assistance.
you're unlikely to find someone who owns both. in fact, i don't own the AirPod pros. but i've owned the AirPods for a year (use them daily, particularly during commutes and calls). and in december, I bought the studio 3 with the big discounts at best buy. I've also been an avid headphone user for the past 15 years. but the AirPods and studio 3s are the first bluetooth headphones i've owned.
in short, the app and the studio 3 serve different needs. that's not to say their uses don't or cannot overlap.
regarding the AirPod pros, how are you with sticking a tip into your ear canals? have you used iems before? i'm not an avid iem user (mainly on long flights). some people (including me) can have issues getting a good seal and keeping it. also, and this is just my personal annoyance, the AirPods are just another thing you have to remember to plug in and charge regularly.
so far, i've really enjoyed the studio 3s... long battery life - especially when you turn off anc. fit won't be as particular as with the AirPod pros. i have a big head, and the clamping force is not bad. and here's a big plus... i love the controls on the left side of the headphones. it allows me to no fidget with my phone. noise canceling is fine - i don't hear a lot of the background noise with them on. but i also use them only at home.
also know that apple/beats is very likely to update the studio 3 very soon. the current iteration is from 2017, i believe. still, it's a great headphone if you got it free. I wouldn't have paid $300 for it.
cheers