There have been many on this board arguing that splitting up Michigan and Ohio State is the "most sensible way" to maintain competitive balance in the conference. I disagree, and I'll point out exactly why here.
Now, Delany and the conference have said multiple times that the criteria for creating the divisions are, in order of importance, (1) Competitive Balance, (2) Maintaining Rivalries, and far off in the background, (3) Geography. They've also indicated that they are only looking at data since 1993, calling that the "Modern Era" of the Big Ten.
So, onto my divisional splits:
East - Ohio State, Michigan, Penn State, Michigan State, Illinois, Indiana
West - Nebraska, Wisconsin, Iowa, Purdue, Northwestern, Minnesota
Included in this split is one permanent "cross divisional rivalry". Those games are, in order of maintaining importance, Indiana-Purdue, Michigan-Minnesota, Illinois-Northwestern, Iowa-Penn State, Michigan State-Wisconsin, and Ohio State-Nebraska.
Now, to deal first with competitive balance. In this discussion, I'm counting Nebraska's old Big 8/XII wins as their "conference wins". While they were in a different conference, the Big Ten and the Big 8/XII have been pretty similar in strength since '93, so that isn't a huge leap. Also, I'm counting Nebraska's conference championships and CCG losses as "conference championships", to make up for the fact that the Big Ten allowed split titles for the entire 1993-2009 time period.
In terms of conference wins, the East has 427 from 1993-2009, while the West is slightly behind that, with 414. Likewise, the East has 17 conference championships to the West's 15(again, counting Nebraska's 5 championships and 3 CCG losses). So, it is clear to me that the two divisions are very evenly matched in this scenario, including splitting Barry Alvarez's "Big 6" teams evenly, 3 and 3.
Next, looking at maintaining rivalries, please notice that EVERY currently protected rivalry game is still played yearly. In addition, three trophy games return to yearly rivalries - the Illibuck(Illinois/OSU), the Little Brown Jug(Michigan/Minnesota), and the Old Brass Spittoon(Indiana/MSU). The Purdue Cannon(Illinois/Purdue) and the Governor's Victory Bell(Minnesota/PSU) do not become yearly battles, but they have not been yearly battles since PSU joined the conference anyways.
Finally, considering geography - in this situation, 5 of the 6 teams in the East are in the Eastern Time Zone, and 5 of the 6 teams in the West are in the Central Time Zone. The teams that are "misplaced" are Illinois and Purdue, which are separated only by some 90 miles, and both are centrally located in the conference footprint, so this is not a huge issue.
Looking at this, we as a conference could have the following games on the last week of the season: OSU-Michigan, Iowa-Nebraska, Wisconsin-Minnesota, PSU-MSU, Illinois-Northwestern, and Purdue-Indiana. It does create the possibility of Illinois and Northwestern or Purdue and Indiana playing in a repeat game for the Big Ten title. However, Purdue and Indiana were last co-champions in 1967, and only Purdue's 2000 team has been conference champions since then, and Illinois and Northwestern have never shared the conference crown, with Illinois having 1 in 2001 and Northwestern in having 3 in the time period(1993-2009), 1995, 1996, and 2000. In the event that those were replayed as conference championship games, there would be enough of a story line and enough of a "newness" factor to outweigh the downside of the repeat game.
As always, if you see a downside to my logic, please point it out to me, so that I can either argue against it or tweak my position to accommodate it.