Widely considered the best part of the original series. Ichigo and his friends invade the Soul Society to save Rukia from execution, culminating in the iconic betrayal by Sosuke Aizen. The Bount Arc (Filler) Episodes: 64–108
If you’d like to dive deeper into specific episodes or need a recommendation for a particular arc: bleach anime list of episodes
A rogue scientist creates clones of the Soul Reaper captains. The Lost Agent Arc (Fullbring Arc) Episodes: 343–366 Widely considered the best part of the original series