The program isn’t as important as how you go about it. I would recommend having some key people at the parish read through Sherry Weddell’s “Forming Intentional Disciples.” That is really the goal. Programs exist to work towards that goal and they can be implemented better or poorer depending on whether or not people really understand that the goal is more than just running a successful program.
I don’t have first-hand experience with the programs you mentioned, but I’ve heard from others that they can be good—depending on how they are utilized. Alpha did not originate as a specifically Catholic program, though I believe they now have Alpha for Catholics. So you would just want to be attentive to whether or not there is some omission in the content and supplement as necessary. If I had to rank them based on what I’ve heard, I would go with Christ Renews His Parish, Alpha, and then Discovering Christ.