The two threads that I linked to both discuss setting up a fire tablet. And, no, it’s not particularly easy but it is doable. The details are in that thread. The specific post I linked to is from last month, so certainly current. 
Since both action tiles and sharptools can run in a browser, it doesn’t matter which tablet you pick in that regard. But again, there is some discussion in the other threads.
iPads are easy, just expensive. They also give you the option to run HomeKit if you are interested in that.
Also, just so you know, in this forum we have many different members with different priorities, preferences, and budgets. And from different countries. So it’s very rare that there is a “one best“ answer for anything. Different things will work for different people. Which is a good thing.
As far as wall mounts, again, lots of discussion in the other threads and budget makes a big difference. There are many really elegant frames available for iPads, but some are very expensive. At my house we just use Sugru.
There are also multiple project report threads in the forum where people have posted what they’ve done, for example:
If all you want to do is use the tablet as a control panel with either actiontiles or sharp tools, you will be only be using the browser capabilities of the tablet, so again, there aren’t too many issues. If you want to also run the smartthings app itself, then you run into some other stuff on the Fire tablet. But that’s discussed in the other threads.