Conker's Bad Fur Day is a better game than Mario 64.
SOLID CONTENDER
Single Player
The biggest advantage Mario has over Conker is the physics engine which makes Mario's movement and environmental interaction so thrilling. His platform ability with long jumps, dives, somersaults, triple jumps, wall jumps, and so on is fearsome. His build up of big momentum is top tier. Everything he touches produces amazement from the shell to slide on, the wings to fly through the depths of 3D, the owl that he grasps to swiftly ascend to the top of the level to drop down onto platforms, the monkey that he snags, etc.
The main theme of Conker 64 is that everything he touches turns bad. In terms of character control Conker's movement speed is one of the slowest of all the big 3D platformers on N64 to my knowledge (Goemon might be the slowest). His jumping comes out nice, not the awful lethargic Rareware had DK do in his N64 Adventure, but Conker moves around too similarly to every other 3D platformer. Normal. Mundane. He has cool abilities to destroy, but not travel.
The biggest advantage Conker has over Super Mario 64 is that its world is better connected and that it challenges the player more. Mario has individual dream worlds while Conker has one big seamless journey. Conker's journey through the world is seamless with the exception of amusing cutscenes, but he never finds anything fun to play with that makes GOING through it to reach new areas less of a toil: only new lives and cash. The physics engine does not let you take advantage of that steep slope to slide or lava to bounce high up in pain in the air. This toil is really felt when one stumbles "off-course": when one gets lost and must now search over high-and-low for the new access point. I have on two occasions gotten stuck by some illogical game design (the cow killing and the pooball rolling - the last one might be a glitch).
There is a lot more to argue about. In terms of sheer impact Super Mario 64 beats out Conker because Conker is too reliant on setpieces and has sharper lulls in between them but never topples the great action Mario has within himself.
Edit:
Vert1 said:
He has cool abilities to destroy, but not travel.
But the multi-player... a bite-sized snack of a world akin to Mario64's levels versus Conker's single player adventure. Another challenging comparison.