I think I could usefully own two more tablets, in addition to my iPad (2). The iPad essentially lives downstairs, in the living room. I mainly use it for web browsing.
I'd also like a small, cheap lightweight tablet with a good, tough shell case for carrying around. Mobile data would be a plus for that one, too.
And then a third one to keep upstairs by the bed, for a bit of Netflix and web browsing when I'm in bed. And a way to read books (PDFs and comics, say) that my eInk readers don't handle well.
That'd be my ideal setup. The cheaper they get, the more likely I am to expand my collection.

The advantage of the Argos and Tesco models is that they have retail stores that I can easily get to, so I'd be able to return or exchange faulty devices.