If you look at the formula for acceleration (a = ∆v/∆t) and acceleration force (F = a⋅m) the only two things we can truly influence here are speed (slower collisions are less dangerous) and time (collisions where the force transfer takes longer produce less force).

The latter is what makes the difference between getting hit with an cushion and an equally heavy rock. The same difference exists if you run against a brick wall and against an angled grassy hill (or: a bendy car hood). Not only will the elastic hood (and the roll) absorb part of the collision energy, the angle of the hood stretches the acceleration over longer time and reduces the force transfered on your body.

So if you get the choice as a cyclist, the choice is pretty clear.