For all the stuff you'd normally use a small tablet for, Android is still the best solution. It has a very large collection of apps & games in a competitive marketplace that helps to weed out some of the more poorly designed or performing software. Android tablets were also brought to market by some big name companies to make a profit, so there is a bit of attention paid to providing a good user experience -- one that would be compelling enough to prompt customers to pay a few hundred dollars [or more].
As these well known name brands pushed on to better & better tech in new models, all sorts of venders started selling tablets made with the tech left overs, all the older & now much cheaper bits & pieces that go into a tablet. They can more or less fill out a shopping list made up of their choice of components that will work together & contract to have it all stuffed in a cheap case & packaged, That means bottom end Android tablets for around $30-$50 on sale, that still perform well enough to gather hundreds [& sometimes thousands] of very positive customer reviews for retailers like Walmart.
One downside shared by most Android tablets however is that the Android OS is generally built, put together for the individual hardware device it'll run on. That work is done by whomever puts the tablet together in the 1st place, so once a name brand tablet is no longer current, that's the version of Android you're pretty much stuck with -- with bargain basement tablets what you get when you buy the tablet is what you get, period. As the core Android system does not get patched the way Windows does, that means as security flaws are discovered in older versions, you're pretty much stuck with those flaws as well.
Windows tablets are a different breed, though at the bottom end you will find devices that are sold either with Android or Windows, with minimal if any hardware differences between them. Cheaper Windows tablets didn't come about because venders decided to try to make a buck in the low end market using leftover tech, but rather because Microsoft & Intel felt it was worth it to break even, or even lose money to keep however many consumers from buying into Android. Nowhere was there any intent to provide an experience that would make you say: "Wow, this is so much better than Android models", or "Wow, I just have to have a Windows tablet".
That's important. Once you have a small Windows tablet most of the things people use small tablets for are out of reach -- simply not possible at the moment. There are apps & games, but not nearly as many, & they're not nearly as easy to find & get & use... A great example, every day on my PC I check out Amazon's free app of the day, & if it's something I think someone in the family will like, I grab it so that Amazon account owns it. I can send it to any one of the devices that share that account, or just leave it there & it'll be available to everyone through the Amazon app. In contrast I have to fire up my Windows tablet just to find out what's available in the app store.
That somewhat sad state of affairs will change a bit. Though behind schedule, Microsoft is working hard on the Mobile version of Windows 10, because they've decided that they want/need to crack the cell phone market. And eventually that mobile version of Windows will find its way onto Windows tablets too. Until then however you're stuck with a desktop OS with the bits added to provide a touch screen friendly start page. The main advantage is that it is full blown Windows on a tablet -- the main disadvantage is that touch is hard [if not downright unusable] with the desktop that makes it worthwhile having full blown Windows... it's the desktop that lets you run regular Windows software.
The advantage to having a small Windows tablet then is having a small, very mobile PC. The one I have is very much like having a low powered desktop or laptop. The 8" screen doesn't matter when I connect a monitor to its mini HDMI plug. Plug a hub into its full-sized USB port & I can use a regular mouse, keyboard, & USB audio device. If I'm not at my desk, often I'll skip the hub & plug in a tiny dongle for the wireless mouse instead. And of course there's always the touch screen without the mouse. With the exception of web browsing, if I want to do something I'd normally use a tablet for however, I pick up my Android tablet, where for example there are apps for stuff like streaming video or watching TV. Even the Kindle app for Android is better IMHO. An Android tablet however will not play the games offered by GOTD on weekends.
Upgrading &/or updating Windows on one of these tablets is usually possible, but I also expect there are & will be a lot of severely messed up Windows tablets from users trying to do just that. The 1st step, if you ever think about buying a Windows tablet, is find out if, how, & how well it can boot from a USB stick. That's how you'll back it up, put things back when necessary, & upgrade/update it. Otherwise you're limited to a reset [assuming that's available], putting things back the way they were when un-boxed.
The 2nd requirement IMHO is 32GB storage. Windows 8.1 & 10 can take up as little as 8 or 9GB, but Windows updates alone can push that to the 20-30GB range, if only temporarily. I use dynamically expanding VHDs for my VMs. What that means is that the VM grows when it needs to, but doesn't take up extra space until then. That 20-30GB range is what I often see after Update Tuesday before I shrink that VHD back down. For Windows 10, Microsoft recommends the minimum tablet storage is 16GB -- that's just for Windows, & nothing else. So while a Windows tablet with 16GB of storage *may* work, & I want to stress *MAY*, you're not doing yourself any favors by not waiting for a deal on a better tablet with 32GB.
Now, the reason for writing this today & not a week or month from now, is that there have been some decent sales on Windows tablets, & there will likely be more & better sales because of both Windows 10 & back to school. Don't assume you can update a Windows tablet running 8/8.1 to 10, regardless what anyone [including Microsoft] says, unless the seller provides [or will provide] an image you can stick on a USB stick, boot to with the tablet, & have it clear the disk & rewrite it with the new win10 image. That said, you might want to stick with 8.1 anyway -- a great many users have come out saying that 8.1 provides a better experience on their small tablets.
Right now, in the US there have been sales where you get a 32GB win8.1 7"-8" tablet for ~$70 with a single user 1 year subscription to Ofc 365, & the Microsoft store even threw in a $20 gift card if I remember correctly. Microsoft is going to continue their program giving away Windows with Bing [regular Windows with Bing set as default search provider], so they'll likely continue the free Ofc promo too.
This summer then might be a good time to pick up a small Windows tablet as a [spare?] PC, as a toy, for a kid in school, etc.