I use Quilt Pro. They just came out with a new version - QP6. I really like it. It is not too hard to learn. I also have EQ7, but I don't like it as much. I am having a hard time learning how to use that one.
What I like about computer programs is you can set up the basic quilt and then easily change the fabric, the settings, anything about the quilt with just a few strokes of the keys. Then you can save the versions you like.
I often draft blocks that I see and save them for future use.