2 and 3 should feel identical - Nav and controller analog movement is the same.
1 feels different because kb input is digital, meaning movement is either 0% or 100% and restricted to 8 degrees of movement. Analog movement however is 0% to 100% along a full 360 degrees of movement.
Aim Assist affects not only right stick movements (mouse aim) but also left stick movement (WASD / Nav). Because digital WASD movement cuts right through AA, you should feel it less than using analog.
What the Fortnite beta firmwares do is make digital movement appear more analog-like (more than 8 degrees of movement and acceleration from 0 to 100%). As a result, AA will feel stronger.
AA should always feel stronger using true analog. But that's not necessarily a good thing as AA can be overpowering and prevent the reticle from breaking into or out of the hitbox. That's why you'll see anti-AA Ballistics Curves on the forums, intended to dampen the effect of AA.
