[EDIT: please ignore this post, it is based on erroneous information (the last sentence/note in the 1st para. is wrong, see CWatkinsNash's correction posts below)]
If you get your magazines free from Calibre's "Fetch news" service, I would suggest a Kindle Fire tablet. Why? Because you can set up Calibre to send the fetched magazines automatically via e-mail to a real Kindle device using your free.kindle.com address. In other words, the magazine just appears on your Kindle device when you get within wi-fi range. Note that you cannot get this automagic delivery to the Kindle app on a non-Amazon Kindle device.
While the above works also with an e-Ink Kindle, you can't page and peruse as quickly, thus the Fire recommendation.
But if your question is about the best print-replacement magazines, then you'll be paying for that experience. Calibre is more about the text of articles, than about reproducing the print pages (including ads) like Zinio does.
Last edited by jj2me; 10-27-2012 at 04:53 PM.
Reason: Post is based on incorrect information.