One thing to consider is that the lighting and the speed of these devices might not be on a par with the Kobo Aura HD. That may well not matter as much to you as the page turn buttons though?
I'd thought about getting the PocketBook Lux, but the slower page turns and not so good light compared to the Kindle Paperwhite shown in
this comparison video puts me off a little.
Not sure where you are and if you'd be interested but Nook may well announce a new e-reader sometime this month, and they've retained the page turn buttons up to now.