I like Franky because he isn’t ashamed to be himself. My brother and I have been watching One Piece and we are half way through Thriller Bark. We both like how Franky approaches problems and situations an an adult, but he isn’t afraid to express his emotions and stay true to himself.
I also enjoyed his relationship with Tom and Iceberg. I think Franky’s past gets overshadowed by Robin’s backstory, but teen Franky tried to stop a moving train in order to save Tom!
Lastly, maybe this was anime only, at the start of Thriller Bark the crew is enjoying the Sunny. We see Luffy, Usopp, and Chopper playing on a swing. I like to think that Franky took one look at Luffy and thought this kid needs a swing to help burn off excess energy while the ship is out to sea. I like how Franky was considerate.