Another thing I wanted to add -- we often underestimate younger people's interest in older media and assume that they're only interested in the latest content, and while that may be true to a large extent, there are plenty of examples of younger people consuming older media en masse. They sometimes have strange reactions to older media, however it would be wrong to say they're completely oblivious to it. The current generation has grown up with everything at their finger tips. Unless you like owning the physical object, and from my experience, younger people are fine with digital copies, then it's never been easier to access past content. 

In the narratives put forth between tarkintinto and supercat, and as someone who read all this off the stands as an avid comic fan, supercat is far more accurate to my experience at the time. Byrne was one of, if not the biggest name in comics for a time. His run with Claremont is wnat made the X-Men the main title for Marvel, which lasted the next 3 decades. Byrne taking over any title was big news.
I don't know how to regard him as an "All Time Great", or how big his influence was. But his footprint then was as big as any artist working, bigger than Perez or Simonson or others. As John Lennon would say, that doesn't mean he was a greater God or man or whatever, just he was more important to the kid's lives.

Jokes aside, in the late 70s and through the 80s, Byrne was THE big name. You saw and heard it everywhere. If it wasn't, then why did people get so grouchy and vocal about his work into the 90s, when he didn't have Terry Austin and Karl Kesel inking? Why did Next Men have such a big following, at the start? Why did he keep getting brought into do projects like the Lost Years stuff?

You can debate the merits of the work of Byrne across his hot period and Adams & Steranko across theirs (and it was a finite period, as they got involved in other things and fandom moved on), but it is subjective and therefore not absolute. What you cannot deny is that Byrne's art sold comics for a significant period of time. Did he originate much? No. Did Adams? The Continuity stuff, but was that ever significant?

Steranko was gone by the time I was reading comics, so I came to him later; but love his stuff. Some of it. I'll take a Nick Fury story over Thongorr or his X-Men issue. Visually, I love his Captain America; but the story is a bit of a mess. Adams was still around, popping up occasionally, when I started reading and much of DC's style was geared towards the Adams look (Irv Novick, Dick Dillin, Mike Grell, etc...) So, I loves me some Adams visuals, from that era. The Continuity material was junk. Badly and bizarrely written, cliched visually, weirdly colored. Steranko staged a really interesting return with Outland.

In the meantime, I loved me some John Byrne, from Charlton up through the 80s and into the early 90s. But, the more he worked at Dark Horse, the less wowed I was, compared to earlier. Muddier art, story seeming to kind of be stuck in place, cranky disposition. I skipped some of his works because others, like OMAC soured me on what he was doing, at the time. Then, he'd do something like Barman/Captain America and I devoured it.

The 80s were Byrne & Perez as the SUPERSTARS, with Miller rising to that status by the end of the decade (Daredevil got him close, then Dark Knight and Year One put him over the top). Those were the names everyone muttered when talking mainstream, while the indies were about The Turtles and Los Bros Hernandez (and Cerebus and Elfquest) and a few other names popping out once in a while. To deny that is to rewrite history. Everything else is down to personal taste. I like Byrnes work through the dawn of the 90s, but I prefer Adams' art and Steranko's design. Between he and Perez, I prefer Perez. However, that is just my preference and it does not devalue Byrne's work.

Some of these kinds of debates seem to hover around the idea that to admit one is good is to devalue the other and to not accept an opinion is to not accept the holder of the opinion. It's an entirely subjective debate. There is no objective criteria by which you can compare art. Therefore, it is just a difference in subjective opinion. No one is ever going to be right or wrong.

I'm a bit late to the party on this, and I wasn't around in the 80s, so my take is all after the fact, but I think that Byrne absolutely did leave an impact on comics beyond just what he drew. There had been big name artists before him, and writer-artists as well, but along with Miller concurrently, he was arguably the first to rise to the level of superstar success that he did. As acclaimed as they were among fans, Steranko's Nick Fury books were never huge sellers from my understanding, and I doubt that his brief stints as guest artist on X-Men and Captain America elevated sales of those titles substantially. By contrast, anything Byrne was attached to sold and got a lot of attention. That level of creator as selling point ushered in a new era of comics and continues to shape the industry today. And Byrne's art was absolutely influential, certainly on the Image guys who were the next big thing. If that influence hasn't extended to artists working today (and I'm sure that it has to some degree), the same is certainly true of a lot of great Silver and Bronze age artists. And I don't think that means those guys legacies are tarnished.

All of that being said though, I don't agree with comparisions to Adams and Steranko on an influence scale because I don't think the impact of his art was as great as theirs was. Adams and Steranko radically changed people's perceptions of how comics could look. I don't think anyone ever looked at a John Byrne page and said to themselves "I never imagined comics could look like that". I think a better comparison would be someone like John Buscema (who I personally think was a much better artist, but that's besides the point). Buscema and Byrne didn't alter anyone's perceptions of what comics as a medium could do, their stuff was just really well drawn and looked great.

Now on to the more important age-old dilemmas... like who would win in a fight between Gamera and Godzilla?