Choose wisely: put pants on one leg at a time, or both legs at once? ~

It depends on whether you can stand on one leg and/or how high you can jump.

The general rule is one at a time. But if you are sitting down you can put both legs through the pants at once up to your thighs, then stand up to get the seat in place.

One leg at a time, do I win?

When I am in a hurry I do both legs at once but sometimes I find out i've put them on backwards. 

Left leg then right leg.

You are losing it, Randy...I asked this question a year ago, but I added two other options. My pants put themselves on. And: I don't wear pants.
To answer your question...left leg, then right.

For long pants, one leg at a time.  For shorts, both legs at once.  

I use various methods for panting my legs.

Both legs at once while standing---keeps me in shape.

Right side, left side, stand up and skooch.

If I were ever to get dressed again, I'd put my pants on both legs at a time.  Like this: