Spherical burgers are there to make them look larger than they are, its pretty much as simple as that. A good burger should fill the bun so you get a bite of beef, toppings and bun each time. A round burger means you get some bites of lettuce and bread and then finally you get to a meatball in the middle. Terrible.

Burgers that swell a lot in the pan are poorly minced and have big bubbles of air in them so they swell up and sometimes pop hot grease every where.

Perfect patty: thick, minced well, flat. Gotta keep it thick so there's a rare/medium center. Now I want a burger.