I browsed through every issue of Esquire since 1971, every issue of Ebony since 2000, and every issue of GQ since 1986 (except for 2005-2009, but I'll get to it). The most striking thing you'll notice if you read the articles, is how different each magazine is under different editors.
You don't even have to read the mastheads to know they changed. And the style and layout of the magazine tends not to change all at once right away. It'll have a transition period of say, six months to three years, and will have a new style, new subtleties, new perks and faults altogether. Same brand and general audience. Different priorities.
GQ, for example, absolutely sucked from 1986 - 1990. Around 1990, the editorial started changing for the better. By 1993, it became something special. I think the magazine's heyday fell somewhere between 1993 and 2000.
Esquire and Ebony were by far more consistent, but also more conservative. So GQ had years when it was the best or worst ever between the three magazines.
I think, at both Esquire and GQ, something happened in the early to mid 1980s when both magazines just got lazy. Perhaps they had too much money and concentrated advertising power in men's media, and they just were fat and happy with all that. Whatever it was, the quality of the writing and subject matter suffered as a result.
Esquire also became a better magazine (again; it was pretty good in the 1970s too) somewhere in the early-to-mid 1990s. And it always had a way with words. I can't think of another publication that made a column on ethics so engaging.
I have a lot more to say about the mags, but don't have time right now. Will eventually. Also need to read a lot more back issues of Ebony. It dates back to 1945. And, given black American history in general, I'm sure it holds a lot of interesting stories, profiles, perspectives.
I haven't gone back far enough to make some sort of mental trend line, but the combination of editorial and design layout for Ebony seems to make a change for the better around 2007. I'm still finishing the issues up to 2010 today, and need to read everything before 2000 when I can find some free time. The additional decades will give me a clearer "mental trend line."