You knew I would, right?
At the time, it was in something of a class by itself, though I can live without about half of the tracks (having heard them all waa-y too many times); Misty Mountain Hop, Black Dog; and Rock & Roll. To some people that would be sacrilegious, I know...
Personally, I think my favorite from that band is
from Houses of the Holy.
My favorite Zep track is the Helmet cover of "Custard Pie" on the Encomium tribute album, although sometimes it's Memphis Minnie's recording of "When the Levee Breaks".