One of the nice things about smarttiles is it seems to work well with pretty much any of the operating systems supported by the regular smartthings mobile app.
Because I am quadriparetic, I only use iOS devices. Accessibility features are baked in at the operating system level and are the same no matter what device you’re using. This has not been true for android.
If you want a cheap tablet to be dedicated to smart tiles and not run anything else, there are android tablets for under $50. The cheapest iOS mini is about $99 now. So that would be a reason to pick android for a dedicated device, again assuming you didn’t need the iOS accessibility features.
So I think it’s just a matter of personal preference.