So, looking at a couple common manual transmission gear ratio charts, first gear would be best. Why? It has the highest ratio. Although it is (in the charts I found) very close to reverse.

Here's a chart for Honda Civics (up to '91 I think)

Here's a PDF from Toyota's press room with their Corolla specs.

Highest ratio = greatest amount of torque applied to the wheels from the crank. Conversely, more torque needs to be applied to the wheels to force the crank to rotate. Also, from my understanding, the forward or reverse gears make no difference except that (is imagine) your motor REALLY won't like being rotated backward. So in that regard maybe it would be better to choose the gear that suits your hill directionality... but at the same time, if you brake and trans fail to hold your car on a hill, chances are things could go VERY wrong very quickly.

So, looking at a couple common manual transmission gear ratio charts, first gear would be best. Why? It has the highest ratio. Although it is (in the charts I found) very close to reverse.

Here's a chart for Honda Civics (up to '91 I think)

Here's a PDF from Toyota's press room with their Corolla specs.

Highest ratio = greatest amount of torque applied to the wheels from the crank. Conversely, more torque needs to be applied to the wheels to force the crank to rotate. Also, from my understanding, the forward or reverse gears make no difference except that (I imagine) your motor REALLY won't like being rotated backward. So in that regard maybe it would be better to choose the gear that suits your hill directionality... but at the same time, if you brake and trans fail to hold your car on a hill, chances are things could go VERY wrong very quickly.