This is the one that I have been using for over a year around the world (I travel frequently for work), and have never had an issue.
Can actually support 4 simultaneous devices, and I've tested it at one point with a Galaxy S4, iPhone 5, Galaxy Note 10.1, and iPad all plugged in at once and charged all of them at the same time.
It's got dedicated ports for a ipad, samsung tablet (presumably a little more juice on these two ports), and two "universal" ports that work for most phones (I current use it with my Galaxy Tab2 and Nexus 5) so you should have no issues with both Nexuses.
Also, the size isn't too bad at all, so very portable. The only complaint -- if you can call it that -- is that the blue led is super bright. Nothing that can't be fixed with a piece of black electrical tape
http://www.amazon.com/Premium-Charg...id=1391552707&sr=8-1&keywords=bolse+quad+port