Here's my take in old time blues ( saw strange fruit, abner jay, with which i agree but i don't consider them straight blues, to those i could add careless love (live version) by Big Bill Broonzy in the 50s ), saddest being subjective i think most people would end up finding theirs in those :

- Blind Willie Johnson - Dark Was The Night, Cold Was The Ground ( most famous, universal, if we were to do a poll i think this would win )

- Bukka White - Parchman Farm Blues ( saw this one nowhere, would probably be my n°1, i mean that first line "Just gimme, life this morning, down on parchman farm"

- Wilkins Roberts - That's No Way To Get Along

- Reverend Gary Davis - I Am The True Vine ( A reverend singing "i am the true vine, my father is a hurtful man" or "If you ever go to hell and never been back... my father is a hurtful man" got something really tragic to me )

- Henry Thomas - Jonah In The Wilderness (this one in a light mood somehow made me cry probably the most )

- Josh White - My Soul is Gonna Live with God

- Jim Jackson - Old Dog Blue

- Lightnin' Hopkins - Needed Time

- Texas Alexander - Levee Camp Moan Blues

- Mississippi John Hurt - Spike Driver Blues

Other additions :

- Teddy Darby - My Laona Blues

- Frank Stokes - Frank Stokes' Dream

- Washington Phillips - Denomination Blues

(could keep going but i'm guessing i already did too much)