Most people had their favorite. The one they played more than any of the others. I mained Arsenal. Not because of how good or bad it was, but because I enjoyed the variety of it. What frame did you like most of all and why.
Back when we could be heal leashes, I spent most of my time as medic. After that I just had fun running around with an assault frame. It was the most fun for me and also had that 'iconic' Firefall look to them, which I liked. I never really got into the medic's design.
At first I was huge into the Assault frame, but I ended up trying all of the base 5. As I stated elsewhere, fell in love with the biotech prior to tier 2 frames. Went with dragonfly after that as I tend to gravitate towards a healer role. Thought the dragonfly weapon was utter crap and went back to using the bioneedler, never looked back.