FKB does a ton of cool things like motion sensing that I am afraid Apple will lock down, but I think iPads are more responsive (Duh they are like 2.5-5X the price so they should).
Used (or look for new ones) Amazon Fire tablets, that are compatible with FireToolBox. Cheap, good quality and a lot of accessories available.
But whatever you end up buying, you need something else to control your charging circles. I have a few tablets running, one is controlled via a Sonoff Basic, the others are plugged into some Zigbee plugs. If the battery level falls under 20% for more than one minute, the charging starts until the HA companion app reports the battery level over 90%. If you won’t look for your battery, you will end up buying a lot of tablets in a short timeframe.
You’re about to outfit your house with touch-screen interfaces
And then I’d take a step back and think this over one more time, because holes of that size are annoying to patch in drywall once you realize that wall mounted tablets are a terrible home UI and noone ever uses them (including yourself). A tablet on a small table or cabinet is less intrusive and easier to roll back (speaking from experience here)
But if you have to, I like my Lenovo tab, because I don’t need to worry about managing battery charging. They have a built in mode to bypass the battery and run on external power only. I just keep it plugged in, charging stops at 60%.
The tablets on the walls are supplemental, not primary. And they’re positioned where we would most likely use them, such as near the entrance to the bedroom, or near the shower (control music.) The primary goal is to have the most important information at a glance, not necessarily to have the ability to control the system, as we are able to do that with voice and personal mobile devices. In some instances, a simple 10" LCD display tied to a video feed from a single Pi3 or some other video output would be fine, but what I’ve found is that our “Dashboard” of information doesn’t have enough screen real-estate, so we need to be able to swipe cards or switch tabs with a touch.
These panels come in both US and EU sizes for mounting in existing switch junction boxes.
I don’t have any yet but this is on my short list of projects. The best place to buy seems to be the eBay Sonoff store. Best prices (and the shipping location is close to where I live.)