You have a good point, in that there were a six good cooks in season one, particularly Harold, LeAnn and Dave with Miguel, Tiffani and Stephen just a cut below. Miguel was a good technician but his repertoire was limited, and he wasn't creative or flexible -- overall, I'd rate myself better. Tiffani had a great handle on food, but I can't imagine her surviving in many kitchens unless the head chef or owner was looking out for her. In most places her coworkers would have strangled her. Don't think that doesn't count, either. Stephen was immensely talented and ambitious (read his CV online), but not particularly dedicated to cooking. You need that.
From the second season it seemed as though there were only three good cooks -- with everyone else far behind. Sam, Marcel and Ilan. IMO Sam was the best of the bunch. Marcel's aesthetic left me cold, plus there was something about him that just rubbed me the wrong way. I thought of him as "the weasel." The guy that won, Ilan, wasn't particularly imaginative -- although very disciplined and talented. At the end of the day, the discipline to not screw it up is what put him over. Elia didn't deserve to be there at the end. She has some strong points, but not enough. I'll never forget "the best booger, ever." [Shudder] FWIW, I knew Betty a little, and my S.O and I ate at her place, "Grub," a few times. "Grub," being a breakfast/lunch place off the beaten path in Hollywood. Not exactly, "fine dining." She's good, but in no way great.