I'm calling shenanigans on the 1984 Gators. They won the SEC. I get that someone said "but the cheating" but they were atop the standings and beat the other team atop the standings. Take your title.
They feel like 2015 OSU in the sense that they got kind of a consolation prize, even if one believes strongly they were that awesome of a team. (In this context, the 2016 Buckeyes are wild. They won a division title without a trip to the title game, got awarded a trip to the playoff, which meant the woodshed. It was pretty successful and didn't totally feel like it)
For UW, it probably has to be 2006. They went 12-1, but missed OSU (undefeated until the title game) and lost fairly comfortably to Michigan (No. 2 heading into the OSU game). They couldn't go to the BCS at 11-1 because there was a two-teams per conference limit. UW went to the Cap One Bowl and beat an Arkansas team that collected losses to good teams (Opened with beat down to 11-2 USC, won 10 in a row, lost to 11-2 LSU, 13-1 Florida and 12-1 UW).
The Badgers schedule was bad and they started slow, but they did win nine in a row. Wins of note were 9-4 PSU and 10-4 Arkansas.
UW had the No. 2 scoring D and top-5 in yards per play. The group was junior and sophomore heavy and just smothered folks. The offense had a senior QB with a totally new set of skill guys. A first-year TE blossomed for 900 yards and both receivers were second-tier quality in program history. The RB was very system, but he did have 1,569 yards and 15 TDs.
For UW, they didn't have a lot of modern era teams that were good by squeezed out before the CCG, and with the west, you almost can't be very good and not go. The 2013 team is interesting, having lost that controversial one to ASU (with an advantage of 2 yards per play), put up a nice YPP edge but couldn't get No. 4 OSU and then had the passing game and defense fizzle down the stretch. South Carolina beat them after their WRs played out of their minds and Stave exploded his shoulder on a defender. That Badgers team had Melvin Gordon, James White, Jared Abbedaris, Jacob Pederson (with the best Joel Stave) with top-13 groups in points per drive on both sides of the ball.