I suggest you watch the following videos first
Secret Origins The history of DC Comics
Justice League the New Frontier, leaving October 1
With that background
I suggest Aquaman 2011
Detective Comics 2016
Superman Lois and Clark
Wonder Woman 2016 Year One - early even numbered issues.
Depends on what you for! I would suggest Super Sons, that’s a good light hearted but fun series. My favorite feature of this app is the storyline section, pick a hero and find some fun stories.
For Wondie: Greg Rucka’s Wonder Woman (#195 of the 1987 series or Wonder Woman Rebirth)
For Sups: All-Star Superman, Superman Birthright
For Bats: Batman Year One, the Dark Knight Returns, Detective Comics Rebirth, Batman (2011) first 12 issues are awesome, the rest is… divisive.
Others: Grant Morrison’s Animal Man, Injustice (imo the best way to get to know as much of the universe as you can. First 2,5 years are the best, the rest gets more meh), 52
Those are the ones that came to my mind. But if you want something shorter and selfcontained I recommend Earth One comics (except for Batman).