Volume six of No Game No Life was indeed amazing, absolutely love that entire series but that certainly was a new height. Currently reading volume 7 as I left off at 6 like a year ago.
As for the others:
Overlord v1 - 10, amazing, have v1 and 2 in hardcover, rest e-book for now.
Spice and Wolf v1 - 2, have ordered physical copies of all of these, just too good.
Log Horizon v1 - 7, also really good but not very different from the anime, still worth a read though.
Altina the Sword Princess v1 - 4, I love the art and the story is decent as well.
Mahouka v1 - 8, tbh I got a bit bored of it after reading eight volumes straight, might get back to it, might not.
Re;Zero v1 - 2, will continue this after I catch up on all the rest.
Serious question to anyone who has read Sword Art Online, is it worth the read if you've seen the anime? And yes, I quite liked it.