I've never known a more ideologically fraught aspect of history where I see every side seemingly more interested in scoring points against the enemy than they are with genuinely seeking an honest interpretation of what it was like on the ground. What are the best ways of finding trusted sources on countries like the USSR, Cuba, Vietnam, China ect without uncritically swallowing red scare and/or red guard lies/spin/ommissions?
So in general anything written on history will always have a bias, it's always worth repeating that mantra.
Anyways, specifically for history of the USSR: while it is a field that continues to develop, it's probably not as politically contentious as one might think, at least from the internet.
I would argue that a good rule of thumb, at least for someone beginning on the subject, is to try to read something written by 1) an academic historian and 2) published in 1995 or later (I say this because these later years incorporate more archival research and also synthesize the better parts of earlier academic arguments). I am aware that this actually would invalidate much of the book list here.
Good works that analyze both the positives and the negatives of Soviet history, but also try to deal with it on its own terms are: Ronald Grigpr Suny's The Soviet Experiment, Sheila Fitzpatrick's The Russian Revolution and Everyday Stalinism and Stephen Kotkin's Magnetic Mountain: Stalinism as Civilization or his multivolume Stalin biography. Magnetic Mountain is a little dense and hard to find, but the rest are relatively accessible and also heavily researched and footnoted. Oleg Khlevniuk is a Russian historian in the Russian State Archives and has written a goos history of the gulag system, and a (shorter than Kotkin's) biography of Stalin.