I’m strictly a Top Hat man.
As a kid, I always had to be the car. Always. That was a deal-breaker for me.
Now, I’m much more mellow about my choice of piece, but I favor the dog or horse.
If everyone I love and I are threatened with the most painful torture imaginable, I’ll grudgingly pick the dog.
I hate Monopoly.
Dog first. Then car. If driven to it, the cannon. Depends on who I’m playing with.
The flatiron. It had that handy handle for moving it around. If that’s not available, the thimble. My brother preferred the car, then scottie-dog, in that order. Nobody in our family liked the cannon.
DD
No one’s mentioned the shoe yet? Y’all are nuts. I’ll go with the shoe first (what better to walk around in?) and the dog second. Canons and top hats make no sense. How on earth is a top hat going to get around the board?
Logistics, people. 
Favorite: the dog or the shoe.
Acceptable: the wheelbarrow or the battleship.
I’m uncomfortable with any piece that metaphorically can’t move. The top hat and the thimble are wrong, wrong, wrong! I would rather not play than be the thimble.
The flat iron is acceptable because it can kind of glide forward. But it doesn’t feel as comfortable as my favorite two.
The cannon is also acceptable because it has wheels and can roll, but cannons aren’t really mean to go long distances so it always so of bothers me.
The car … you’d think I’d love the car but it’s too obvious. It’s a little kid’s piece.
The horse … we didn’t have a horse in the set I had when I was a kid so it feels wrong even though it meets my criteria.
I never had a favourite. Any piece was fine. It has to be at least 10 years since I played it anyway.
Yes!!! Great minds think alike!!!
I also like to be the shoe.
But being the youngest, it seemed to be whatever was left.
The dog. If it’s taken, the top hat. Our flatiron piece had the handle broken off it years ago so we always called it the surfboard. No one ever chose the surfboard.
People, the top hat moves because you’re rich. The rich can make anything happen.
Personally I would never park my car on Baltic and Mediterranean, and the damn dog is apt to get run over at those four railroads. Plus, how do you take a ride on Reading Railroad if you’re a car??? What are you, freight? One shoe makes no sense unless you only got one leg.
I always liked the thimble. It was all the dimples (as well as its frustum-y shape) that did it for me.
After that, I liked the shoe. It looked most authentic to me.
I was afraid of dogs as a child, so I shyed away from any symbolism as such.
In a related vein…
I’m amazed to be the first person whose number one choice is the battleship. My other choices, respectively, would be the shoe, the car, the dog, and the iron. Beyond that I don’t much care, except that I refuse to be the thimble. I will import a foreign object into the game – generally a piece of whatever snackage happens to be handy – rather than use the thimble. Every time I have ever been the thimble, I have suffered a devastating and nigh-comical (for the other players) loss within the first 15 minutes.
On a side note, I am Lord of the Street Repairs. I will get assessed for street repairs. It will happen. I don’t even hope against it anymore. For me, street repairs just…are.
The top hat is the one I get pissed if I don’t get. If someone wants to cross me and doesn’t let me have the top hat I’ll be the shoe.
The Scottie Dog always. My brother always took the race car, so that was never an option. At some point we lost the dog, so I was left to play with the iron. Those were dark days.
I always used the wheelbarrow. I had to carry all that cash, you see.
I don’t care if it’s a little kid’s piece: I like the car.
Vroom-VROOOOM! Wheeeeeeeeeee!!!
I used to always be the horse.
Then I got the set that had a train! I love being the train.
Or the money bag. In my newer sets that’s the one for me,
Or the tornado. Gotta be the tornado if you’re playing the wizard of oz game…
Or R2D2. I mean how cool is he?
Or Woodstock.
Taz…
Ok I have a problem. I’m an addict. If it has the monopoly logo on it I need it. I just got some socks this weekend, and for Valentine’s day I got the coolest Monopoly charm bracelet…