In the beginning was The Plain Truth. That's if you don't count the Bible Advocate.
These days the PT - cut loose from the Tkach church - is unavailable outside the US and Canada, where it promotes a weird "religionless Christianity" gospel for a small fringe readership. In its fading shadow many pretenders have arisen: the Good News (UCG), Tomorrow's World (LCG), Vision (COG-aic), the Trumpet (PCG) and - reinventing the wheel - WCG's Christian Odyssey... these are the flagships of the fleet, the way the various Churches of God present themselves to the world at large, dripping wholesomeness and cheap wisdom, garnished with a pretense of biblical competence and prophetic insight.
A lesser known contender is Armor of God (CGI). I'm not sure how many print copies circulate - probably not a lot - but if you're curious you can always download a copy. Although issued irregularly, it compares well to its bigger siblings in concept and design thanks to the undeniable talent of Shey Smith (in comparison Tomorrow's World looks almost geriatric.)
Content? Well, that depends what you're comparing it to. Depending on your perspective the articles are either fresher or goofier than the big boys churn out (or possibly both)... it's certainly hard to imagine references to ancient worthies like Polycarp and Polycrates making an appearance in the Trumpet, for example.
CGI's first flagship magazine was the ill-fated Twentieth-Century Watch, launched in 1980 (with an innovative cover price of $1.25) and then sinking like a stone. TCW featured well known ex-PT writers like Garner Ted Armstrong, Brian Knowles and Gary Alexander, but Armor's by-lines are far less familiar: there's apparently a shortage of aging Armstrong-era identities on tap.
Though, with reference to the current lead article, perhaps a future edition could include a feature called Just what do you mean - Boyne Again?