Although I am not totally familiar with all of his works, my all-time favorite poem is "Sea Fever" by John Masefield.
Robert Frost's "Stopping by the Woods on a Snowy Evening" is another favorite.
Robert Service's poems, though somewhat on the dark side, have a comic edge to them, and are fun.
And for sheer grins and giggles, it has to be Ogden Nash.
When all is said and done, it is difficult if not impossible for me to choose a single favorite. ;-)