The 745 Pub is great. 745 Mass Ave. Good food and great wait staff. It does get busy which is always a good sign. Right across the street from the IFD museum and union hall.
Called the Mass Ave Pub now after the rebuild but I will second this. I love their bacon cheddar burger.
Mann's Grill on the southwest side. turkey manhattan or Mann's breakfast
The lunch buffet @ The Amber Indian near Meridian & 126th is incredible.
The Datwich @ Gumbo-a-go-go is also killer good. 86th & Ditch I think.
Not 'downtown' but Boogie Burger in Broadripple makes some killer burgers.