Pro Football Talk posted the top four worst moments since 1987 for the Titans/Oilers franchise (apparently it is franchise history day at MCM). Only two of them are from the Titans era. They are the 2008 AFC Divisional playoff game against the Ravens, and, of course, the Super Bowl loss to the Rams. The other two were the 1989 AFC Wild Card game and the 1992 AFC Wild Card game (numbers 4 and 1 on the list respectively).
The 2008 divisional game hurt a lot for sure, but to me the 2000 divisional loss to the same Ravens hurt even more. The 2008 team was really good, but they weren't anywhere close to as good as the 2000 team in my opinion. That team was dominant pretty much all year long and had lofty expectations. That wasn't the case for the 2008 team.