Since platformers are my favorite genre, I like this thread. :)
My favorite platformer and favorite game of all time is DCK2. It has been since launch and probably will always be. Previous favorite was DKC1.
Other favorites are: Mario (all besides sunshine), the 1st 3 Crash Bandicoots, Rayman, Megaman, Ducktales (NES), Little Nemo: the Dream master (NES), B.O.B (SNES), and A Boy and his blob (Wii)