How should I choose between Photoshop and Procreate for professional illustration?

[MatthewDG]

I've been using a basic, free digital painting software for a couple of years to create character illustrations, but I'm hitting its limits with brush lag on complex canvases and a lack of advanced layer blending modes. I'm ready to invest in a professional tool and am torn between the industry-standard power of Photoshop with its massive plugin ecosystem and the more intuitive, iPad-friendly workflow of Procreate, especially since I do a lot of my sketching away from my desk. For illustrators who have used both extensively for finished portfolio work, what were the decisive factors in your choice, and how did you navigate the learning curve and potential additional costs for brushes or add-ons to build a toolkit that matched your specific style, whether it's painterly realism or clean line art?