Tommy! They are both very cute and I don’t think it’s fair for Timmy to loose points for being extroverted (even though I’m an introvert myself), it would be pretty annoying if they were both outgoing and pushing you to buy stuff! Tommy’s cute little small font repeatings are probably all he wants to do. Tommy still wins in my books though, he is a killer flag holder and is perfect in his shy role.
I believe they're the same looks wise, but I have to go with Tommy. He's always in Timmy's shadow, echoing his words. Sometimes I make special efforts just to talk with Tommy instead.
I always tend to like to talk to Tommy when I can help it since Timmy is the generally more talkative one. I myself have always been more timid and quiet, and was especially so when I was younger, so I guess I just want to go out of my way to be nice to him since it's sort of relatable. Plus, as others have mentioned, Tommy carrying around the flag in the early game was cute.