Cutter's Bar & Grill in Eastern Market
The word "best" is often very subjective.
Reddit Detroit readers are asked: What's the best burger joint you've been to in Detroit? Here's some answers:
casscanfield: Cutters in Eastern Market has some delicious stuffed burgers.
msu06: Motor City in Hamtramck.
SirMikan: Jay's Stuffed Burgers in Plymouth is my favorite, though it's far from town. They put some crazy stuff in their burgers, but I have yet to be remotely disappointed with anything I've had there.
ColWalterKurtz: Griffin claw does make a good burger to go with their delicious beer.

Burgers at Grey Ghost Detroit
DetroitPeopleMovermidtown: Checker Bar is the best I've had so far. Been to most of the commonly cited best burger places except Cutter's and Motz's.
yodasw: Never see it mentioned, but Andrew's On the Corner in Rivertown has one of the best burgers I've had in the city. No frills, perfectly cooked and seasoned. Also from one of the oldest restaurants in Michigan.
Valongatzhamtramck: Campau Tower in Hamtramck is a great late night spot for a greasy burger. Lots of weird topping options and atmospherically it's really tiny and full of perfect weirdos.
UncleAugie: The burger at the Bronx bar in midtown has been stellar for a decade or more. It is the Bun, amazing from a local bakery.
JoumanaKayrouz: Mercury. Outside Detroit is Travis on Mack and 9.
Brandon48236: Telway on Michigan.
ornryactor: My favorites are Greene's and Brayz. Greene's cooks the onions crispy and gets the edges of the patties with a nice crisp, too. Nobody else does that. Brayz has the best onion rings, an inexplicably good chocolate shake (when their machine isn't "broken", which is like half the time), and uses much better pickles. In the same vein, I see noticeable differences between the two Telway's. Yeah, lots of the white castles (ever wonder where the franchise got its name?) all fall into a middling pile of identically average, but there are a few standouts on each end of the quality spectrum. Personal preference in what you like in a slider accounts for a lot, though.
iThib: Nemo's is always great, and I like Anchor Bar too. Anchor Bar is great for a cheap burger and a beer. Just old-fashioned flattop burgers. Of the newer restaurants, Standby and Grey Ghost have two of the best pricier burgers in town. That said, I haven't been to Standby since the first chef left. They might have nixed the bacon on the new burger. Grey Ghost is like a Big Mac, but won't leave you with a stomach ache.