In this thread, I would like to collect some ideas about what would comprise a good, "usable" open operating system running on a tablet.

Here's my situation: I'd originally planned on diving into writing apps for the Jolla tablet, which I'd hoped to have received last summer. But, of course, it's now winter, and given current circumstances, I'm not sure I'll ever receive the tablet. So, I'm trying a new tack: I'm now planning on picking up a cheap Nexus 7 tablet, and installing something other than Android on it. If this requires me to do some UI coding myself, so be it; I might as well spend my energies on that, if Sailfish is going nowhere fast...

So, here are some questions to consider:

1) Use Mer or not? I think there are a number of advantages with Mer, but given that the initial target here is a tablet, maybe a full-blown desktop distribution of Linux would be doable...

2) Assuming Mer is chosen, what UI to use:

a) Sailfish? I'm kinda hesitant about even touching Sailfish at this point, as it may soon end up entangled in Jolla's death-throes, and is in any case way too big for just a handful of open-source advocates to maintain. But it really is a beautiful UI...

b) Nemo? Support for this UI seems to have dried up, but it is cleanly open today, and seems more lightweight than Sailfish. I want to at least give it a try.

c) Hildon/Cordia/etc.? It'd be really nice to see a Maemo-ish interface come back again. (And it includes stuff that I really like: extremely light-weight UI elements, lots of support for alternate input methods -- such as stylus and keyboard, support for widgets, etc.)

3) Given a particular OS and UI, what features are essential? I myself demand a decent terminal and shell. But my guess would be that tools like a web browser and e-mail client would be significant for most users. Media players as well. Again, I'm not a tablet user, so I don't have a good feel for what people do with these things...

4)The fun question: what could we do differently? For example: one thing that absolutely every phone OS designer has chosen to do is to kill tasks whenever a memory overrun is threatened. This is, of course, to ensure that you can always use the device to send and receive phone calls. Without the need to protect the phone functionality, a tablet UI could reasonably return to standard memory paging techniques to bring true multitasking back to mobile devices...

Anyway, let me throw the floor open for comments here. If you had the chance to put together your own tablet with your own OS, what would you want to see?

EDIT: I don't think I put enough of an emphasis on the idea that this is a question about what you, yourself would like to see in a mobile OS, not what you think would sell as an OS for the general market. So, I've modified the thread title a bit...