I don't think I have any favorite deaths.
Unless we count the Pre-DC Spirit. Or the Spirit Archives, since they were printed by DC.
Then I'd say Gerhard Shnobble.
As for least favorite deaths:
(Tie)
Sue Dibney
Tora Olafsdotter
Ted Kord
Maxwell Lord
Dmitri Pushkin
Vivian and Constance D'Aramis
Rosabelle Mendez