FiveThirtyEight looked at this earlier in the month and showed that the Cubs were the 26th best regular season team ever. http://fivethirtyeight.com/features/the-year-of-the-cubs/ And of the 25 teams above them, 13 won the World Series. So if you combine best regular season team with a World Series title, the Cubs hypothetically would be the 14th best team of all time. If you only want to consider teams since the invention of divisional play in 1969, the Cubs are the 4th best team in the last 47 years, behind only the 1998 Yankees, 1975 Reds and 1970 Orioles (the Reds and Orioles are both just in front of the Cubs, the Yankees way ahead)