Sigh. I broke down and bought an Apple 10.5" iPad Pro with all the bells and whistles for about a grand. It has 512 GB of memory and a T-Mobile SIM card. I also got the Apple pencil and their keypad.
Why would an affirmed Open Source/Android guy like myself do this? Because I have two Android tablets that are unsupported (after less than a year), and hence are too insecure to use. It is a scandal that Android manufacturers are not required to update security for at least 5 years. Say what you will about Apple, but they support their devices until the hardware becomes unworkable. My main computer is a late 2010 Mac Pro (bought new in 2012) with 32 GB of memory and about 20 TB of disks. It still runs the latest version of MacOS.
I took about a week to get used to the iPad and its quirks and idiosyncrasies. I like it a lot, especially the build quality and performance. Alas, the very legible, bright screen is a fingerprint magnet. As you can tell from the above image, I am running the IOS 11 beta, so my comments will refer to this incarnation of the operating system. While on the image, the keyboard, which attaches magnetically, types very nicely. There is an amazing amount to key travel for a keyboard so thin! The best feature of the keyboard is that it acts as a stand to hold the iPad at the correct reading angle when I read lying down in bed. It would be too heavy to hold otherwise. The horizontal 2-column view in Kindle perfectly mimics a paperback book. I did have the iPad fall out of the magnetic clutches of the keyboard once already, so do not rely upon holding just the keyboard and its case, but keep a grasp on the iPad as well.
My biggest complaint with IOS is that (unlike with Android) there is no user-accessible file system. Apps can make files, and you may access them, but if you wish to transfer something other than a media file of some sort, you are in trouble. I have about 1 TB of high-resolution music files on my Mac, and certainly do not want them synchronized with my iPad. In fact, I have a directory of MP3s I keep for just this purpose, but figuring out how to transfer them was really hard.
Luckily I found an app for that - File Manager Pro from zuhanden.de. It allows you to make a samba connection with your computers, and do rapid file transfer this way. File transfers using iTunes are really slow, and it is very hard to find the option that lets you do this.
Notice that it has SMB connections to my Mac and to my Linux server (JARDELL). And, I can see and communicate with all the many disks on my Mac. I used this app to transfer my 64 GB of MP3 files to a Music folder, and iTunes on the iPad found them all. I am a big fan of old-time radio shows, and they are included, along with my classical music files. The iPad is really wonderful when used on my NordicTrack along with iFit. I can listen to Jack Benny or Our Miss Brooks while I exercise, and it is loud enough to overpower the fan noise.
I also stream music several ways. I subscribe to Tidal's lossless stream. Tidal is incredibly hard to use if you like classical music, but once you figure it out, it is a great resource. There are about 50 versions of Carmina Burana in the Tidal library. But there are also many obscure works and classic performances of familiar works—you just have to know how to find them. I also have my own Subsonic server, and use play:Sub on the iPad to listen to my high-def home collection anywhere I go. The speakers on the iPad (two on each short end) produce loud, clear music, albeit the bass is lacking. They switch their stereo channel when you rotate from landscape to portrait mode.
Finding apps that actually work is a chore. I run a jabber server (ejabberd) so that my friends and I can chat in private. I tried Boogie Chat, Monal, Trillian, and IM+. None of them would connect to my server. Finally I found Talkonaut that was dead easy to set up, connected properly, and also will allow me to make phone calls. It is frustrating how many apps out there that do not work properly.
I am a scientist, and using the Apple pencil to write equations on the iPad into Evernote works really well. The 10.5" size is just right for writing on. And Evernote does OCR so you can search for hand-written things.
Another thing that does not work is keyboards. Apple IOS refuses to respect my preferred choice of keyboards (SwiftKey) and comes up with the Apple keyboard in all Apple apps, and for passwords. This is really not nice. And yes, SwiftKey is at the top of the keyboard list.
And guess what? For me, Android apps are far superior to iPad apps. For example, I rely heavily on the app WiFi Overview, which plots the signal strength of everyone on every channel. (see https://blogs.jamesrome.net/AC5400, for example.) There is nothing like it in the Mac iTunes store. I also hate the games. I badly miss Word Run Pro. Most iPad games have awful, childish decorative stuff all over them. I went and bought Minecraft, only to find out that to actually use it, you must to pay a monthly fee! Luckily, Apple refunded my money.