Agreed. It's not the editing software that makes the shot, it's you that does it. You can use all the software in the world, but if you don't have any decently shot footage, its useless.
Post processing is the cherry on the cake. Make sure its a good cake.
On a mac you have options, Premiere from Adobe (paid), FinalCut Pro from Apple (paid) and Davinci (free), but like the guys have said above, learn to fly it first doesn't matter how much of a cutting wizard you are, making something filmed badly look good is a LOT more dificult than something filmed well (any of the DC Movies for example)