I have some gripes with the Boox tablet I have and I have never owned a kobo reader (though I do hear very good things about them).
My main complaint at this point is that I don't like that it requires so many proprietary apps that need to connect to the internet. You used to be able to remove pretty much all of them. But now you are forced to keep some or the device won't boot.
I did find that it's pretty much impossible to brick the thing because it just reloads the firmware if it errors out.
And yeah I suppose you could just go and block those apps from the internet on your router so they can't send or receive information.
But for an android device running an outdated android version I'm not sure it's worth it to spend the $400 or so on a device that lacks such control when Kindles exist and can be jail broken.
I can't say (having owned one) that I would ever buy another one.