Ex-Aid didn't have the strongest final arc (that prize still goes for Drive), but one can easily make an argument for it having the best season finale of Heisei.
Emu actually became a mature, reliable person whom you can believe will keep his promise of shouldering all the lives lost to Chronicle. Hiiro finally learned the lessons Saki wanted him to learn. Taiga made amends with his past and can look forward to having a future. Nico had an awesome conclusion. There were no asspulls for the villain of the heroes, last battle was cool looking (that delayed continue!).
Top 5 season without doubt.