Pick your favorite.
I can’t choose just one myself, so, Top 11.
“Ten Years Gone.”
Honorable mentions go to “No Quarter,” “Rain Song,” “When the Levee Breaks,” and “Carouselambra.”
This is my second-place song, third place is Bring It On Home.
But tops on my list is The Lemon Song. Just nasty musical fornication.
The Ocean should be on the list as well
I’ll be the first one to take the boring choice: Stairway to heaven. Not a top favourite of mine, but my favourite Zep song by far.
Whole Lotta Love is probably my favorite. It’s just fantastic, really. The bass, drums, crunching guitar and even a theremin. Though the credit for the lyrics must go to Willie Dixon.
Way better than the overplayed Stairway, which is probably my #3 or even lower. Kashmir’s my #2.
I’ll pick one not on your list, track one, side one, album one: “Good Times, Bad Times.” I never get tired of that one. “Ramble On” would be a close second. Don’t much care for Stairway, though IV is my favorite album.
Kashmir.
So many others.
When the Levee Breaks.
Another vote for “When the Level Breaks.”
Also “Dazed and Confused”
Hard to pick just one. My top three:
No Quarter
Nobody’s Fault But Mine
Bring it on Home
The Rover
Seconded.
“Achilles Last Stand”, “The Immigrant Song”, “Fool in the Rain”, and “In the Evening” move the needle for me. I love a lot of stuff already mentioned, too … hard to pick a dozen faves, much less one. 
Houses of the Holy. It rocks!
Lemon Song for the bass line.
Rain Song. I sing it to my dog when it’s raining because he hates rain. I’m not sure whether it soothes him or irritates him, but it is a distraction.
“When The Levee Breaks”, followed closely by “Kashmir”.
**Kashmir **is #1 for me but I love so many Zep songs.
In no real order …
Whole Lotta Love
Black Dog
Dyer Maker
Kashmir
Stairway to Heaven
Immigrant Song
All of My Love
Over the Hills and Far Away