The reason that Snyder is in the conversation (and only in the conversation) is that his winning percentage at KSU is 50% higher than that of any coach at the school since the 1930's. He's had KSU #1 in the country twice. At one point, KSU went 72-15 and finished ranked in the top ten 5 out of 6 years while coaching in a power conference. KSU has never been in the Top 25 in their entire history except when he was coach. The coaches you listed are all in the conversation for greatest all time without a doubt as well but none of them had to deal with the situation that Snyder had. In 100 years of football, KSU had been to one bowl game. They've been to 16 bowl games with Snyder as head coach. As much as we enjoyed Mike Price as a coach, imagine if he had won 116 games instead of 83 games and finished in the Top 10 six times instead of three times. As coug fans, I would hope that you would appreciate the accomplishments of a man who won at a place where nobody expected him to win more than guys who were just one of the guys who was successful at a place that was used to winning.
Guys like Saban, Meyer, Carroll, Bryant, Hayes, Miles, Switzer are all terrific coaches and all are certainly worthy of being considered better than Snyder, but the colleges that they coached at are places where championships were happening before and/or after they were coach there. Florida, USC, Alabama, Ohio State, Oklahoma and LSU are places where a competent coach is always in the conversation for a national championship. If you say that Snyder is inferior to them based on winning percentage or national titles, you are saying that any coach at a non-elite football school has no chance of being considered very good.
Paterno, Bowden and Harbaugh are a different breed because they legitimately built up the programs that they had success with. FSU and Stanford were bad programs and they raised them to levels that hadn't ever been seen before. You could argue the same for Carroll at USC because the Trojans had been in a funk by their standards and they haven't been the same since he left. Still, USC won four national championships with McKay as coach and by that measurement, he isn't even the best at his own school. Joe Pa raised Penn State to a level higher than any other coach in their history before and after.
All of the coaches mentioned above are worthy of being the greatest coach ever and I won't expend any effort in saying that Snyder is "better" than them. Again, I'd like to think that Coug fans wouldn't look at national titles and winning percentage as the only ways to measure a coach. If so, man, we've had a lot of really crappy coaches.