I had forgotten about the Google Nexus because I don’t have one. But it is also atop the “Best of” lists as well.
Unless you’re really pining for an ipad, I would focus my attention on the Samsung and Google tabs.
Jerv brings up a good idea for those who are tech savvy. However, you should be aware that if you’re not tech savvy ENOUGH, no matter how good any of the jailbreaking apps are, you can end up “bricking” your tablet. You are then the not so proud owner of a very expensive paperweight.
I don’t want to take the chance but only you can determine if this is something you can handle. It does save you a few bucks, but that’s about the only clear advantage I can see.
Basically, jailbreaking removes the Nook or Amazon’s attempts to restrict you to their own little universe (obviously to their profit.) but ANY other major tablet does the exact same without the risk.
Whatever you do, stay away from those really cheapo Chinese knockoffs. Getting a tablet for $50 or less only seems like a good idea until you realize that the app for Google’s appstore is not there. That’s the primary source of all major apps.
However, Amazon’s appstore is pretty good also (but far less regulated). But you don’t have to buy a Kindle Fire just to have access to the Amazon Appstore. There is an app available which can work on any other tablet and if a technotard like me can follow the instructions to get it, then anybody can.
The primary reason I made the effort to get it is because of Amazon’s FAOTD. That’s the Free App of the Day and even tho there are a bunch of .99 games free for a day, usually there’s some really good productivity apps or educational ones worth $5–9.99 normally about once a week on average. And all their apps have free cloud storage if you ever change devices in the future.