I am a giant fan of Chicago Hamburger Company's sliders, with cheese. After five or six you can get a bag of 10 for 10 bucks. Can't say I've ever made it past six... but I certainly have tried.
I truly believe that I may have been able to tolerate the weather here in PHX a little better for all this time knowing that this place is also here. Also, the fries are the perfect combo of crispy and potato'y and always served blazing hot. Wife is a big fan of the chili cheese fries- super delicious. Also try the banana shake.
I hope they have something like this place in the afterlife. In my mind they are tied for best slider in the USA with White Manna in Hackensack NJ.