As with all the sources I like, The Nation publishes a lot of stories involving solid research and nuanced analysis, and while they publish opinion essays their news stories don't seem to be promotional for liberals/radicals. (They're big on Bernie.)

Something I think works pretty well for me is looking at conservative takes on material I read in left sources. Often there isn't any. Often, it's denialist claptrap or attempted character assassination. But sometimes they make a point I'm glad I've read. And the lack of such strikes me as a form of verification.