Bleach
To put it bluntly, the Bleach anime had a largely bad run.
Plagued with filler and ended on an anticlimactic note, it left all but the most die-hard fans dissatisfied and wanting more.
This was worsened by the fact that it ended right before the series’ final arc, wherein it saw some of its most evocative villains and themes.
As such, a Dragon Ball Z Kai-esque remake would do the series wonders. Not only could it cleave away all the unnecessary fluff, but it could also adapt the sorely missed content left out of the show’s original run.
Not only that, but it could improve on the flaws of the final arc as well. While many of the final fights in the manga were bombastic and epic, there was a rushed sense of pacing that plagued it down to the final chapter.
A full adaptation remake could alleviate this, giving the arc more room to breath and develop as an enjoyable pace for viewers.