Miller's Daredevil, Grell's Green Arrow and O'Neil's The Question are peak street-level superhero comics
I'm currently rereading Mike Grell's Green Arrow (actually I'm rereading the first omnibus, haven't read the second one yet), and man, that book is awesome. I love the grittier tone and more serious storytelling (even if there's still some silly stuff in it sometimes). It has aged pretty well to be honest, especially writing wise. I'm usually not a big fan of older art but I can handle it just fine in this series. Same goes for O'Neil's The Question, which shares a lot of similarities with Grell's GA. Daredevil is obviously a bit less grounded, but the tone is very similar, and I'm sure it inspired Mike and Dennis.
Obviously most DD runs fit this bill well, and the recent Green Arrow run by Condon is also excellent. Shoutout to Ed Brubaker's Catwoman, which also is a great street level hero book.