You'd probably like a British show called 'in the line of duty' 2 seasons so far.

The show was Against the Wall and I really enjoyed it. It was played more as a soap opera, with the main characters issues with her family and her love life being more front and center. But it also wasn't just about finding corrupt cops, but about proving good cops innocent - like when a cop is accused of murdering his wife, etc.

There was a 6 or 8 episode series like this in Lifetime 2 or 3 years ago. Two women partners, one of the women came from a family of cops and caught hell for joining IA. Her reasoning was that she had just made Detective and the only spot open was in IA.
I don't remember the name of it, but her cop father was played by Treat Williams, so you can take it from here.

There was an excellent British series in the 90s called
Between the Lines (1992)
which was about a police investigations team and the issues they face in investigating other police officers.
Worth a watch if you can find it where you are - there are 3 series, the first 2 are excellent, but the less said about the 3rd the better.
Never trust a hug, it's just a way to hide your face.

Definitely an interesting idea for a TV show (or even a mini series). Movies featuring police corruption often portray anyone from Internal Affairs as unlikeable and immoral a-holes (although the movie Internal Affairs with Richard Gere and Andy Garcia was one of the few movies that portrayed Internal Affairs in a good light).

I have watched a couple of episodes of Chicago PD and haven't found any good guys in it. So I gave up.

We are used to police shows that show Internal Affairs as the bad guys so it would be a shock and a good idea for them to have a show make them the good guys. Chicago PD almost does it. If well written, it could be done.

Alternately, it could be a season-type show. The focus could be on just how difficult it is to expose particularly slippery corrupt cops. I'm thinking something along the lines of "The Killing", where a single antagonist dominated each season.
"Fluoride doesn't prevent tooth decay. It does render teeth detectable by spy satellite." -JL

Maybe as a 13-week miniseries with a group of stories that would have a climax. I can see a weekly procedural about IA boring even me pretty quickly. How many people would want to watch a show that leaves them with the impression that the police force is generally corrupt? Other cops looking askance at the protagonists and occasionally complaining that they're cops chasing after cops would wear thin soon too.
"He IS Redstone."

Don't know if people would buy it, but it certainly would be different. It would be nice to see IA cops doing what they're supposed to doweeding bad cops out of the force.
Be even nicer if it would happen in real life.

Yes, and I think it's a tired cliche of said police dramas.
I do think it would also take some extremely well-written characters to make Internal Affairs-centered shows work. As you said, IA guys are traditionally portrayed as antagonists.
"Fluoride doesn't prevent tooth decay. It does render teeth detectable by spy satellite." -JL

Most episodes of police dramas about Internal Affairs make the IA guys out to be villains, going after the innocent, well-meaning cops just trying to do their jobs to make the streets safer. It would take a major change of POV to make the IA cops the good guys.
Chicago PD might be a good place to start. There don't seem to be any good guys on that show.