The 12 team era is shortest in Big Ten history lasting only 3 years. The 2nd shortest was the 7 team era which began when the conference started in 1896 and ended when Indiana and Iowa started playing in 1900 (4 years later). Here are various football stats for the period.

Big Ten Championships
2-Wisconsin (2011, 2012)
1-Michigan State (2013)

Big Ten Divisional Champs
2-Michigan State (2011, 2013)
2-Ohio State (2012, 2013)
1-Nebraska (2012)
1-Penn State (2011)
1-Wisconsin (2011)

Best Overall Big Ten Record (not counting Big Ten Championship Game)
2-Michigan State (2011, 2013)
2-Ohio State (2012, 2013)

Overall Records for 3 year Period (not including Big Ten Championship Game)
Ohio State 19-5 (19-6 with BTCG)
Michigan State 18-6 (19-7 with BTCG)
Nebraska 17-7 (17-8 with BTCG)
Penn State 16-8
Wisconsin 16-8 (18-8 with BTCG)
Michigan 15-9
Iowa 11-13
Northwestern 9-15
Minnesota 8-16
Purdue 7-17
Indiana 5-19
Illinois 3-21

Note: This includes Penn State stats that the NCAA considers vacated. I'll be dammed before I use stats that inaccurate.

Edit: Correction to information at the top. The 7 team era lasted 4 years as Iowa and Indiana did not start playing Big Ten football till 1900.

Who would you guys vote for as team of the era?

For me, it's a narrow win for Michigan State over Wisconsin.