In this year's Final Draw, which partitioned the teams in a very even manner, the toughest Group has to be Group F.
Group F
Germany
Mexico
Sweden
Korea Republic (South Korea)
The Germans, of course, are the defending champs, and the recent winner of the 2017 Confederations Cup. Even without those accolades, they're always a favorite. But, the reality is they have many returning players from 2014 who are in their prime, with the same coach, who is a brilliant soccer mind, and nothing seems to be holding them back from a rare World Cup repeat title run. (Only Italy and Brazil have accomplished such a feat, in 1934, 1938 and 1958, 1962).
Mexico arguably has the best team in their history, with too much talent on the field at one time, including Hernandez, Guardado, Corona, Herrera and others. Despite their second round curse in past World Cups, they have the potential to make huge strides in Russia.
Sweden without Ibrahimovic will not be much to write home about, however, they are a solid team which put Italy to bed in the Preliminary Competition two-game playoff.
South Korea is one of Asia's most consistent performers. If they can find some 2002 magic they'll be on track. Regardless, this team right now is a solid one, and like Sweden, they have the capability to overthrow anyone at any given time.