Which inclines take more energy to climb? Slow and gradual or quick and vertical?

At which point do they equal out?

the energy level is the same to attain it, just a matter of time/exertion

the energy level is the same to attain it, just a matter of time/exertion

The energy required for going up would be equal, but the gradual slope would require more overall energy because you're also moving forward.

Friction notwithstanding. Forward motion doesn't matter in the long run.

Are you taking into account energy used for just existing (eg a human being), or energy that gets wasted by going faster (eg in a vehicle subject to friction losses)?

That was my first thought...does the "engine" operate at equal efficiency under different loads/slopes/etc?

Somehow I doubt the OP will be back with an answer, but if I am wrong, more power to that person.

I mean, let's just take the modifications out of the picture (gears, levers, etc) and just go with what I would call its natural state....

Same circumstances for both

Which would use less energy?

What if we are talking about an engine that is low in torque, but decent in being a Linear Motor...or whatever it is that is opposite to the torque motor.

You can't really match torque to efficiency, though. Torque is a measure of angular force, effectively. The torque of an engine is not related in any predictable fashion to the efficiency of the energy conversion of the engine.

Assuming this is about a car, then ideally, I think you'd want to be running the engine at its most efficient point (in terms of converting the chemical power of the fuel to mechanical power), which will be at a certain engine speed, producing a certain power and torque (torque * engine speed = power). Then be in the lowest gear the car has, and then match the incline so that the excess power over what is needed to keep the vehicle moving at that speed is devoted into increasing the potential energy, ie height, of the car. Being in a low gear means the car's losses due to air resistance etc. are kept to a minimum, because it's 'forward' speed is the lowest of your choices.

If time is precious, energy consumption is rather moot.

that'll give you your answer

You'll have to spend a certain amount of energy on the vertical displacement, and that will be the same no matter what path you take. But, on the gentle slope you'll have to spend energy overcoming friction for a longer time, and you'll spend more effort supporting your load against gravity.

So I'd say, as long as you can generate sufficient power, take the short steep route and get it over with...

Between the beginning and the end.

for some reason.