Shane is not even in the discussion with Efren. Reyes was the best ever one pocket player, the best ever eight ball player, one of the best ever at nine ball, highly capable at both straight pool and bank pool, and he always seemed to win when the prize money was highest, such as the IPT $500,000 first prize and two scores of over $150,000 in winning the Japan Open. His win over Earl Strickland, who was at his very peak, in a race to 120, further validates his pedigree. We may never see another one in Efren's class.
It's no secret that I'm no fan of Earl, but I can't deny his pedigree or his resume. Like Shane, Earl also won 5 US Open 9-ball events, but unlike Shane he won 3 WPA World 9-ball Championships, and he won 10 Mosconi Cups. He won countless PBT and Camel Tour events, all of which featured large, super-tough internationally diverse fields. Obviously, I have no idea whether you saw Earl at his best, but he was famous for dismissing champions (Sigel, Varner, Hall, Bustamante) by scores like 11-1 and 11-2 on a regular basis in competition. He was the most dominant nine ball player we've ever seen. Shane doesn't measure up to Earl.
As for Sigel, I think that in the modern era, he is America's greatest player. Sigel and Mizerak were 1A and 1B as far as the latter part of the straight pool era, and Sigel and Strickland were 1A and 1B in the early part of the nine ball era. To have been so thoroughly dominant in both the straight pool era and the nine ball era is a feat that only Mike can claim (with due respect to Rempe and Varner, who also continued to excel after the straight pool era drew to a close). Had he not retired young in about 1994, I think Mike Sigel might have compared favorably with Efren as the greatest ever player, but I can't put Mike over Efren. Finally, Sigel didn't beat fields that were easier than what SVB has faced, as in Sigel's early campaign, winning a top event meant beating fields that included Steve Mizerak, Nick Varner, Dallas West, Allen Hopkins, Irving Crane, Lou Butera, Jim Rempe, Danny DiLiberto, Ray Martin, Luther Lassiter, Jimmy Moore and Joe Balsis. Yup, all twelve of them are in the BCA Hall of Fame today. Beyond that, such fields included the likes of Pete Margo, Larry Lisciotti, Dick Lane, Tom Jennings and other confirmed world beaters. Sigel triumphed over some of the toughest fields ever seen in pool.
Your list has the right four, but I find it impossible to put Shane over any of the other three.