[Nook HD, HD+ Q&A, Help & Troubleshooting] br0adband:
I'd say the Nook HD/HD+ would be better in that respect: you can install a custom ROM on any Nook HD/HD+ inside of 10 mins without any issues. I just grabbed a marked down Nook HD from a pawn shop a few days ago for $12 because nobody wants 'em anymore. Got it home and knowing that it had been powered down for probably 6 months or longer when in the storage area of the pawn shop then on the shelf for a few more months (based on the dates on the sticker) I let it charge to 100% then I came here to this subforum looking for the current method to install CyanogenMod on it.

My Wife has a Nook HD going on nearly 3 years now, no issues with it, been running CM11 for a very long time and it works great but I figured if this "new" one worked well with CM12.1 I'd redo hers as well.

In 5 minutes I had the 4 necessary files downloaded:

- the boot files that need to go on a blank microSD card (with the partition set to Active so it's bootable)

- the TWRP recovery (the card itself will boot from Clockworkmod which is part of those 5 boot files) but you're installing TWRP to the EMMC (the flash memory inside the Nook HD/HD+)

- the CM12.1 archive

- the Gapps for Lollipop

Formatted the card, set the partition active, copied the 5 boot files (with the MLO one being done first which is a crucial aspect of it working), then the other three archives as well

Powered down the Nook HD, disconnected the power (so it wouldn't reboot), put the microSD card in, powered it up, went into recovery, did the "factory wipe," installed the CWM recovery build to the EMMC internal memory, then flashed CM12.1 then the Gapps and powered down.

Booted up, voila, CM12.1 and it runs extremely well without any hassles whatsoever in another 5 minutes or so for a grand total of ~10 minutes invested. The result? Performance is much better than CM11 on the same device so because of that I redid the Wife's Nook HD in the exact same manner using the exact same microSD card in about 5 minutes.

Now we've got semi-identical Nook HD tablets and they both work great.

If you choose the Kindle route, you end up having to do more research because of the wide variety of the models available, and some of them do NOT have custom ROMs at all (the Kindle Fire HD 7 that I recently got from the same pawn shop for only $5 was the 2013 model that has no custom ROMs because it just can't be done) and you also end up having to deal with issues of the bootloader on some devices and potentially bricking them so... the Nook HD/HD+ are practically unbrickable by design because they were meant to boot off the microSD slot first which is what makes it so easy to install custom ROMs on them, thankfully.

I strongly recommend Nook HD/HD+ hardware if you want to do any "hacking" or custom ROMs. I can't speak for the newer hardware that B&N uses now from Samsung, I haven't used one and haven't even seen one but I know that because they're basically Samsung tablets that means you'll end up dealing with Knox at some point, bootloader problems, and so on.

But in terms of ease of use and "hacking" ability, the Nook HD/HD+ are still amazing for just how easy it is to upgrade them to a better performing and vastly more capable device in 10 minutes or less.

Hope this helps...

ps

The method I used is featured in the PDF file available in the first post in this thread:

http://xdaforums.com/nook-hd/general/install-cyanogenmod-12-1-barnes-noble-t3211119

which also provides the necessary links.