Maurice and Henri Richard dominate given the number of championships, their lengthy careers and their talents as players. At the same time Marcus and Damon Allen are indeed worhty of mention, regardless of which league Damon played in (CFL); 70,000 yards passsing is still remarkable!
How about Sandy and Roberto Alomar? While Sandy has endured a solid career as a starter and backup (Rookie of the Year and one All-Star performance), Roberto was a sure-bet HOFer for over a decade and one of the best second basemen to ever play the game (multiple All-Star performances and Gold Gloves).
If you would like to limit it to American sports, i have no opinion. But in terms of world sports, i think the best set of brothers can be found in Cricket.
Be it the Chappells (Ian, Greg and Trevor) who represented Aussies in the 70s and 80s, their cousins from the Kiwi land, the Hadlees (Richard & Dayle) or the Amarnaths (Mohinder & Surinder) from India, they all were very good but were upstaged by the aussie twin pair. Born a few minutes apart - Steve Waugh (most capped aussie captain) and Mark Waugh (one of the most elagant players of all time) appeared in a total of 100+ tests together and played together for Australia for more than 10 years. If there was a HoF in cricket, both will be first ballot entrants.
Don't forget about the Conacher trio. Lionel played for the Toronto Argonauts (CFL), and was a member of the 1921 Grey Cup winning squad. For 12 seasons, he played for the National Hockey League on the Pittsburgh Pirates, New York Americans, Chicago Blackhawks, and Montreal Maroons, winning the Stanley Cup in 1935 with the Maroons, as well as spending time coaching the Blackhawks and Americans. He also excelled in lacrosse, baseball, boxing and wrestling, and was in 1950 named Canada's top athlete for of the half century.
Charlie won a Stanley Cup, two league scoring titles, and five times led the NHL in goals playing for the Toronto Maple Leafs on the famed "Kid Line", and was voted the 36th best player in NHL history recently.
Roy won two Stanley Cups, and led the NHL in goals and points in 1949.
All three are Stanley Cup winners, members of the Hockey Hall of Fame, and Lionel is also a member of Canadian Football and Canadian Lacrosse Hall of Fames. Lionel's son Brian and Charlie's son Pete also spent time in the NHL.
I must preface this by saying I do not consider them the best siblings in sports history.They're not Hall of Famers or perennial superstars,but the "Catching Molinas" all have World Series rings.Bengie and Jose with the Angels and Yadier with the Cardinals.Championships are what its all about.
i think with your assertion that there tends to be more hockey siblings than other sports may pertain with the systems in place to excel in each sport.With the other profesional sports, Academia plays a major part in the assention of players and talent. Hockey is a sport that is more recreational by nature in its entry level form thus siblings introduced to such sport tend to be much more common