I'm out to buy two tablets for my oldest kids, aged 7 and 5.
The main problem I have is that on mainline tablets, like the one I have, Samsung Galaxy Tab3, I can't control the installed software, and not only certain apps, but also software I can't remove,
With root you can remove those annoying software packages.. Maybe you say you can't because of warranty?
They are certainly going to spend some time playing games, looking at Youtube, etc., but the main reason they are getting it now is that the smallest one should learn writing in a more joyful way than handwriting. And there are medical reasons for that. And then, it would be unfair if the older one didn't get it too. The most important activity shouldn't put much strain on the CPU or graphics. All I need is a 9-11" screen, a USB port and Wifi.
So, I'd like to hear your recommendations, are there any not very expensive devices that would work well?
What do you mean by "not very expensive"? That's kind of subjected. When you get into the 9-10 inch tablet size you do see a jump in price. I probably can't really recommend something without asking a bunch of questions, but I can give you some advice. From experience point of view as a parent, and what I went through with my two boys.
They probably won't be multitasking so you don't really need tons of memory. 1gb is the least amount I would ever buy. Those super cheap tablets with 550 or so mb of memory will frustrate your kids, as their games will lockup and freeze on them. ( my experience ) youtube videos will stutter. Eventually they won't even want to use the tablet. If you can afford it look for 2g ddr2/or ddr3, but 1gb ddr2 is ok.
Battery is probably just as important as memory. Anything less than 4000 mAh won't last more than 5 maybe 6 hours running games and videos. TOPS. They never last as long as they say they do. Right now, you're probably saying "that's enough". BUT, the first time they put down the tablet with their game/video/movie still playing and run off to the bathroom and return 30+ minutes later, ect..., or if you plan on taking them in the car on trips or anything like that, you'll be glad you went the extra mile and got one with a little bit more juice.
The screen matters! cheap tablets sometimes have crappy displays.
They're kids. buy the drop and spill. My youngest son says "oops!". a lot. The extended warranty has paid off for us.
Buy something they can use now, that doesn't look like a "baby toy" (there are some cool tablets for kids in all kinds of colors but kids think they're for babies) because they will grow out of it fast and not want it anymore. Especially your 7 yr old. Let them customize their tablets with skins that they can change as they grow instead..
A good tablet will last them a long time if they take care of it. So put a shock resistant cover on it for sure! I let my son pick it out, then he didn't complain when I put it on, and he was a part of the process.
#1 piece of advice... buy a refurbished tablet from a reputable seller and buy the drop and spill. If you're in the states Wal-mart is a great place to start. NO ONE can beat their NO questions asked drop and spill 2 yr. extended warranty. And their refurbished items can be returned if you're not happy. I've bought a few tablets, laptop, and a wireless printer. Can't beat them. They all have looked brand new. AND you get a much better tablet for the money, as they are discounted in price. If you're not in the states try nuegg. They are reputable. I never have bought from them, but know others who have. They offer an extended warranty, don't know about it's pricing though.
PC magazine and Laptop magazine both have a list for recommendations to buy and to avoid.
I'd probably look for a nexus 9 refurbished. Root it. Take out the junk. Put in the kid's stuff and parental controls. Turn off root permissions.
There! way too much of my two cents. And I did recommend one after all!!