I hope you don’t mind that I’ve moved your post from the Show off Your Dashboards thread into another related thread about which tablets people are using… if you scroll up a bit in the thread, you’ll find some relevant feedback!
The most popular tablets tend to be Amazon Fire Tablets, Apple iPads, and Samsung Galaxy Tabs (in rough order). Though any device with a modern web browser should work fine.
Amazon Fire Tablets
I think the Amazon Fire tablets are probably so popular based on being a good ‘bang for the buck’. They’re relatively low cost devices and have decent performance. There are definitely much more powerful devices out there though not at as good of a price. The Fire Tablets also have a decent number of options available for wall mounts on Etsy, Amazon, etc.
There’s also some neat apps like Fully Kiosk Browser which make it easy to wake the tablet on motion, set a screensaver, etc. Note that there are some limitations to the Fire tablets. For example, they cannot be automatically unlocked which means that you can’t let Fully Kiosk Browser let them go completely to sleep - the workaround most people use is to dim the screen as far as it will go on a black screensaver. (Normal Android tablets don’t typically have these same limitations)
Apple iPads are also very popular. The new models are pretty powerful and there’s a wide variety of mounting options available for them. Relative to the Fire tablets, iPads are more expensive and the mounting options tend to be more expensive as well. That being said, they tend to be smooth / well performing devices.
While there isn’t a single stand-out “Kiosk” app that people use for iPads, it seems like a lot of people are happy with the Add to Homescreen approach.
As you noted, some of the older generation iPads might have some quirks. (The same really applies to older tablets of any sort which is why we generally recommend using a newer model tablet if you can - the newer models tend to be most performant and have support for the latest web standards)
Samsung Galaxy Tabs
The Samsung Galaxy Tabs share much in common with the Fire tablets in that they have access to the same apps like Fully Kiosk Browser which enable wake-on-motion and screensaver functionality.
The big difference is that Galaxy Tabs tend to be a bit more expensive than the Fire tablet counterparts… though their higher end models may be worth the premium as you get a more powerful device with a better quality screen.
Beyond that, I’d really leave it up to the community for their recommendations and experience. We’ve seen the community using a variety of other devices from RCA tablets that are occasionally on sale at Walmart to purpose-built in-wall tablets and more.