Hanging the bike by the front wheel means you don't have to lift it as far,
bike's weight heavier on the back , but ...

you have to use a hand on the frame, to lift the weight, and another on the handlebars ,
to keep the front wheel straight so as to catch the hook..

If you hang it from the back wheel you have both arms to lift the bike
and the rear wheel will not flop around in the process.