I love trees ... reading each post I thought for nearly every one "no, THAT'S my favorite tree!"
It's difficult to choose a favorite. Willow would be up there though. I don't have space to devote to one, but I would love to have access to the branches for all KINDS of things.
I planted a tulip tree (magnolia soulageia ?) on my daughter's first birthday, and since I don't have that house anymore, I planted another one for her 18th birthday. They are usually blooming on her birthday, and I used to take her picture with her tree each year when she was growing up.
I love lilacs, but they don't grow here.
Birch, cedars, maple - Japanese or otherwise, camellia, rose of Sharon, empress trees, mimosa, chaste tree, black pine - these are favorites.
This house came with oaks and palms. I've planted fig, pomegranate, persimmon, (I want plum!), crepe myrtles, rose of Sharon, and a volunteer that I'm not quite sure what it is yet. I need to put those morning glory tree seeds in pretty quick.