A bot bumped this post, then I had something to add, then the bot's post was deleted before I could post.
Anyway, decades ago when I had a Sailor Moon fansite, I actually composed a list of episodes I deemed essential for the DiC dub. It differed from the lists others compiled at the time. Rather than let the compilation rot on my hard drive, I'll post it here, dub titles and all. I actually presented the episode list in alphabetical and sequential order, but because that would be redundant, I'll just post the sequential order with my (old) justifications here:
"A Moon Star is Born" -- First episode of the series, and first appearance of Sailor Moon, Luna, Tuxedo Mask, and several important supporting characters.
"Computer School Blues" -- First appearance of Sailor Mercury.
"An Uncharmed Life" -- First appearance of Sailor Mars.
"Nightmare In Dreamland" -- Raye meets Darien for the first time.
"Fight to the Finish" -- Jedite's defeat/Nephlyte's first appearance.
"Match Point for Sailor Moon" -- Maxfield Stanton (Nephlyte)'s first appearance. Zoycite's first appearance.
"An Unnatural Phenomena" -- Raye and Darien start to get closer.
"Dangerous Dollies" -- Raye and Darien are shown as a couple.
"Who is that Masked Man?" -- Tuxedo Mask's identity revealed (to the viewers). Sailor Moon learns Maxfield Stanton is Nephlyte.
"Worth a Princess's Ransom" -- The Silver Imperium Crystal is brought out as a major plot point. Malachite's first appearance.
"Molly's Folly" -- Nephlyte begins to develop feelings for Molly.
"A Friend in Wolf's Clothing" -- Nephlyte's death.
"Jupiter Comes Thundering In" -- First Rainbow Crystal episode
"The Power of Friendship" -- Second Rainbow Crystal episode.
"Mercury's Mental Match" -- Third Rainbow Crystal episode.