The three-wheeled ones take some getting used to. You can't take turns at a high speed or you'll tip over. They are nice when you are standing still, because they stay up-right. They are easier to turn-around on foot: the front wheels are closer to the centre of mass, so you can easily lift the back wheel and swing it around.
The two-wheeled ones are faster, and handle more like a normal bike. When fully loaded (100+ kg) they take some effort getting them on the stand. They are clunkier to turn around.
The three-wheeled ones take some getting used to. You can't take turns at a high speed or you'll tip over. They are nice when you are standing still, because they stay up-right. They are easier to turn-around on foot: the front wheels are closer to the centre of mass, so you can easily lift the back wheel and swing it around.
The two-wheeled ones are faster, and handle more like a normal bike. When fully loaded (100+ kg) they take some effort getting them on the stand. They are clunkier to turn around.
I prefer the two-wheeled ones.