"Call of the Primitives" and "The Golden Lagoon" are my favorite Transformers cartoons. This is a really fun episode with a mix of action, Grimlock humor, and insight into the Transformers universe (albeit perhaps incongruous with other revelations). As a child, I devised a plot wherein Tornadron must be recreated in order to fight an overgrown Dweller, an energy-draining creature imprisoned then released by the Quintessons in the bowels of Cybertron. Obviously this story must have left quite an impression to have stirred my creativity and to now recall the episode clearly, 20 years later.
Note also that this is the only episode featuring the Terrorcons (yes, another cheap marketing trick, but these were pretty cool toys!).