He is not the greatest coach ever in terms of strategy, in game decision making, etc. I'd take Spurrier over him any day in a game between the two with similar talent on both sides.
Spurrier had elite talent at Florida every year and won "only" one title. And as others have mentioned, Bowden had his number.
As good as coaches like Spurrier, Bowden, Paterno, etc. were, you can poke holes in their records if you get really nitpicky. Spurrier struggled against his big in-state nemesis Bowden and won only a single title. Bowden, as dominant as his teams were, "only" won 2 titles despite finishing in the top 5 14 years in a row at one point. Paterno, for all his longevity, only won 2 national and 3 conference titles. Bo Schembechler, who Michigan fans will tell you is Spurrier, Bowden, Paterno, Saban, and Urban rolled into one,
never won a national title and was 2-8 lifetime in the Rose Bowl. Each of those guys have incredible reputations that precede them, but it seems like each of them should have won more than they did, right? You can even play that game with coaches in other sports...check out Dean Smith's record at UNC.
But what's the hole you poke in Saban's record? That he was mediocre early in his career at a middling Big Ten school that was on probation? That he lost in a CFP semifinal once to the team that ended up winning it all, or Dabo beat him once in a title game? Cam Newton beat him once in the midst of a Heisman, national title-winning season? Manziel beat him once that year he won the Heisman and put together one of the greatest single seasons in CFB history? Sure, those are "holes" in his record if you want to call it that, but they seem really small compared to the other coaches I just mentioned.