Cement for Fence Posts

I was curious on everyone's thoughts on techniques for pouting concrete for fence posts. I live in the Chicago area and will be isntalling a fence. I am digging down 48 inches, adding 6 inches of gravel and then will be cementing the 4x4 post in the ground. I have seen this done two ways:



1) Pre-mixing concrete in wheel barrow then pouring it into the hole



2) Use quick set cement where you pour the bag of dry cement in the hole then add water



Is one way better that the other?



Thanks,

Tom

Cement for Fence Posts