I've only been to the 5-8's once but I've been to Matt's many times over the years for their Juicy Lucy's. They were always one of the best joints around up until a couple of years ago when they were unfortunately getting to be bland. I was thinking that I was going there too often and eventually stopped going all together. It wasn't until I was corralled back in due to a family get together and it was surprisingly like the old days and then I realized what the difference was. If the guy is at the grill turn around and come back later. Seriously, I swear it's the cook. It's been him every time and when he's not there it's great.
Lions Tap in Eden Prairie is also a good place for a burger. They don't have Juicy Lucy's, but good non the less.