I love all the old Spongebob's. The new ones suck way too much.
Favorites:
The Night Shift(where the KK is open for 24 hours and Squidward tells that ghost story)
When Spongebob and Patrick learn to swear
When Spongebob, Patrick, and Squidward get captured by the Flying Dutchman.
The one where Squidward has to watch Gary and they get "snail plasma" and get turned into snails.
Pretty much all the old ones. *misses old episodes*