This is a fairly straightforward plot-focused episode, wherein Steven considers serious Gem matters with the same sort of care as Connie’s favorite book series.
Maximum Capacity
In which we explore the fascinating relationship dynamics between an oddly like pair: Greg and Amethyst.

Winter Forecast
This episode features a neat concept taken in increasingly serious directions (but it all ends well).

Horror Club
Steven just wants to have a fun scary movie night with his (human) friends. Not in this show.
On the Run
Amethyst is doing stuff she knows that she shouldn’t be (and encouraging Steven to do likewise), meaning something is really bothering her.

Future Vision
Garnet tries to connect with Steven by sharing her secret superpower…and fails spectacularly (or does she?).

The Test
This is a deceptively simple episode that marks something of a turning point in the narrative.

Alone Together
This episode is just quintessential Steven Universe, and I’m pretty sure it’s what finally made me a fan.
Warp Tour
Big changes are looming on the horizon, and Steven is the one with the unfortunate task of warning the other Crystal Gems.

Lion 3: Straight to Video
This is without a doubt the best thing to come of the direct-to-video fad.