There is no such thing as the best poem. It is all very subjective. The best poems can have any number of themes.
the poems theme
Disneyland is the best park ever
JOHN CANE beter answer the jeopardy theme
yes
Invictus
Crapsey's and Plath's poems both address the theme of death.
Best Night Ever.
wind
Some poems with bereavement as a theme are: Book of Ecclesiates - A Time for Everything, Do Not Go Gentle Into That Light, Remember, Epitaph Upon A Child That Died.
love poems.
movement
The theme for the 2013 Doodle 4 Google competition is "My Best Day Ever..."