I personally use Amazon. But I rarely download directly to my Kindle. I download to my PC. Use Calibre with the DeDRM plugin. Then put it on my Kindle. Or read it on my iPad. That way I’m not locked into any one ecosystem. I get to own the books for as long as I can keep the data.

I’ve heard DeDRM also works well with Adobe’s protected epubs. But I don’t have direct experience.

If Amazon ever makes it impossible to strip the DRM, then I’ll probably switch to buying physical books and getting files from LibGen. Or just using the library more.