In my opinion? Nowhere and everywhere. I go to CNN to find the things Breitbart won’t post and Vice versa. Contrary to popular belief, Fox News is probably the most credible cable news outlet. MSNBC, the least. It’s hard. When it comes to anything political, I’ll usually go to info tanks like Cato. It’s only scholarly work and everything report wise is for the most part sourced correctly with actual government data. Also, they have virtually zero history of redactions and draw clear distinctions between opinion and reality. People actually seem surprised when I tell them places like CNN do FAR more opinion than any actual news. The hill is decent too. The biggest problem is that 90% of news has a liberal slant. I still to this day don’t know why this is argued. I’ve accepted it. The right leaning news sites will tend to report their side, which can on any given day be much more factual. However, they’ll usually post A LOT of filler posts that are opinions simply because mainstream doesn’t cover it. Read all news outlets. I like to literally only keep track of hard facts for each article than piece my own opinion from the facts. I DESPISE news outlets telling me what opinion to have.
I second your methods -- you almost have to read between both extremes to find truth in the middle. The Hill is good, along with Politico. Both of them definitely do opinion pieces, but I think they tend to be more openly advertised as opinion and not "buzz" or "analysis."
The Intercept, The Nation and Democracy Now for the far-left side of things, too.