Half Rez 2016
This was my first, and I wasn't even planning to go to Half Rez, but all the planets aligned and I found a super cheap flight out of Seattle, and a great deal on AirBnb. I got to half a night of Cinema4D and a small vacation of Chicago. I recommend it if you can swing a similar deal.
It's a little hard to explain. Everyone there is passionate about C4D and graphics; you're all in one room listening and watching the favorite things of what you do. You see people that you've been following online for a while, and it's different than other presentations like NAB, or Siggraph. It's more laid back. It's nice.
Chicago is pretty fun too. It doesn't feel as constricted by land as other cities like Seattle or Manhattan. The zoo is free, and the subway is great. There's plenty to see and do. :)