Ohio is the only state with multiple teams that has them all/both in the same conference. Having them in the same division is just silly. So who do you move?
The Bengals have won the AFC three times. The Browns have won it zero. The Bengals have won the AFC North six times. Browns have won it zero. There’s a history with the Bengals and the AFC, while all of the good things in Browns history come from their time as an NFL (pre-merger, now named NFC) team.
It seems obvious to me that Cleveland should be kicked over to the NFC for the reasons listed above, along with a natural rivalry with Detroit in all other sports. The real question is which team makes sense to switch spots with them?