The pragmatic answer for most people, because the free tier is real rather than a trial. Canva will generate a deck from a prompt, but its actual strength is the library underneath: thousands of designed templates, a huge stock of images and icons, and AI tools that fill, resize and restyle what is already there. For a deck that needs to look decent rather than be argued over, it gets you there with the least thinking.
Its pure text-to-deck output is a step behind Gamma's, tending toward generic layouts that need rearranging. And with this much in the interface, finding the right feature can take longer than using it. But no other tool gives away this much, and the export options, including to PowerPoint, are the most reliable of the web-first tools here.