Found this fun info in the Kid Zone, Stats since 1949. Ottawa's was not accurate (only current stats, none from before the Fold) so sorry gade fans. After the team the numbers are for Games Played, Wins, Losses, Ties, Points For, Points Against and GC wins.
B.C., 839, 382, 434, 23, 18875, 19265, 4
Calg., 902, 455, 429, 18, 21398, 20071, 5
Edm., 910, 540, 352, 18, 22074, 18591, 12
Sask., 908, 419, 466, 23, 19891, 21763, 2
Winn., 935, 489, 434, 12, 21180, 20187, 10
Ham., 860, 421, 422, 17, 18909, 18567, 15
Tor., 872, 387, 471, 14, 18901, 20039, 15
Mont., 716, 339, 356, 21, 15075, 15506, 7
Based on those numbers the all time winning percentage teams:
Edmonton 59.3%
Winnipeg 52.3%
Calgary 50.4%
Hamilton 48.9%
Montreal 47.3%
Saskatchewan 46.1%
B.C. 45.5%
Toronto 44.0%