I'd be torn between Erudite (b/c I like to research and learn) and Dauntless.
Just to warn you, the author's writing style changes just slightly in Book 2, but vastly in Book 3. The character profiles change too. Four is less tough guy and Tris is less shrinking violet. Their love story is still good, but there's much more arguing in book 2. It focuses more on Tris's struggles with the death of her parents and Will and how she's going to tell everyone she killed her friend. The upsets in Book 2 are very interesting and shocking to say the least. I was very surprised by some of the plot twists.
Book three bounces back and forth between Tris's POV and Four's POV. It's difficult and awkward at first, but I think, now that I'm on chapter 34, that it's necessary so you understand their individual struggles and given the way the book is supposed to end (do not read Amazon reviews if you don't want the spoilers). Again, the character profiles shift slightly - Tris becomes angry and Four becomes depressed because of things they learn in Book 3 about their world and themselves. It's been a tough deal being more objective about book 3 after loving book 1 and 2 so much (book 1 is by far my favorite) but it's readable and I still find myself fully engrossed in the book even after putting it down - i.e. not able to fall asleep right away, thinking about it all throughout the day, etc. It's been captivating despite what I've said above.