Since it's 3:07, I' doing 2.
5. Dream Hoppers
In this dialougless episode, SpongeBob chases a walking and (sort of) talking Krabby Patty into his friend's dreams. The main reason I like this episode is because it feels original despite it being a ripoff of "Sleepy Time." Now we move on to number 4.
4. SpongeBob's Last Stand
In this environmental episode, SpongeBob tries to save Jellyfish Fields. I just love it. This is where it gets to WHY CAN'T THIS BE LONGER level. Funny jokes, such as Krabs raising his claw all because he likes saying "Aye!" and the song.
Hint for 3: A TV movie