Hello and thanks for the comment!
It's a hard question you got there. And I can't give you a straight out answer right now, I gotta let that one sink in. But as far as character development goes I can tell you what I'm proud of in general.
I like all characters motivation to fight the empire/Khronos. (With the exception of perhaps NHG-73, but he/She don't really need any motivation since it's a robot.
I also like how all characters have their own play styles. Everybody can be useful in both defense and offense depending on how you want to build them.
As far as dialogue goes I enjoyed writing lines for Rhen, just like a child he made up his own words for things he had never seen before. (Calling the sun a "light orb" is just one of several examples).
It was also fun to make up all those cheesy jokes Nadine tells from time to time, jokes that only she alone appreciate.
Writing lines for NHG-73 was challenging, since his vocabulary is limited. Challenging but fun.
I can write you back with a more specific answer when I've had time to make a better analyze.
Regards!