I'm only just finishing series one of the Japanese Sailor Moon, but with just that there are so many favorite moments its hard to remember them all.
But I would have to agree on Nephrites' last scene with Naru as being one of the best, oh poor Naru it was such a sad scene, I think I fell for her the most then, and every scene with Naru and Umino are the best too, they are so cute together.

Any fight between Rei and Usagi deserves a mention, just cause they are so funny and cute at the same time.

Oh and this one fight scene I think will forever be my favorite, in episode 31, where Zoicite is collecting the rainbow crystal from the cat and he/she goes after the little girl instead and when she/he traps the girl in a small alley, then Sailor Mercury, Jupiter and Moon find Zoicite and prepare to battle. Ah the fight scene is so funny cause they are trying to fight Zoicite but are squashed into the alley and Usagi hits them with her 'ill punish you' pose, then Ami falls over from her attack then Jupiter almost zaps them all with hers, and the look on their faces

yeah truely I think that, that scene is the best and my most favorite.
Also the fight scene between Jupiter and Dark Endymon in the episode were they are trying to collect all the crystal holders again is good, plus Ami's battle in that same episode.
The missing episode when Usagi is fighting that bat youma, Kyulene, and uses the stage sound system to deflect the sonar attack that was good, also when she entered an 'adult bar' and ordered a creamy soda, that was so funny.

Oh I could really go on forever on just season one of the Japanese episodes, havent even reached the dub yet

so I'll just summerize the rest.
-Scenes with Naru in them
-Scenes with Sailor Mercury in them
-Scenes with Ami in them
-Scenes when Ami does this ¬¬ (there are few)
-Scenes when (ok I guess you get the picture

)