Kimi No Iru Machi Ok this doesn't fit but for those reading
Spoiler (highlight to view)
I adore Asuka and would love for her to have a happy ending. She's just so cutely boyish and sporty. The fact she is the most flat chested of the heroines makes it even better for me. Weird I know.
A main heroine like her would just make me so happy. W-Juliet could fit but she gets girly later. Still good tho.
Just looking tomboyish is not enough btw. So avoid series like Ouran or anything like that. She needs to act "boyish" too.
A scenario I would love is the tomboyish girl having a crush on the main guy but being too scared to say it and being forced to watch him w/ other girls and getting really jealous. Even better if he does something like pat her on the back and call her his buddy. I sort of have a thing for what I call reverse-netorare. Seeing the girl jealous, sad, angry and forced to see her crush w/ someone else. Of course I do want a happy ending though.
I just find it so cute when the least girly girl gets the happy ending. Same thing in reverse. I love seeing the guy not many of the girls want get the happy ending. (ex: Monkey High!)
Btw I mean the stereotypical manga tomboyish girl. Rough way of talking, shortish hair, hangs out w/ guys, loves sports, dresses sporty, etc.