Well, the answer to your question depends on if you are going to breed your own or not.

If you aren't going to breed your own, normal rats are better because they are easier to come by. If your normal source goes away, you normally don't have to look very far for another one.

If you are going to breed your own, then in MY opinion ASF's are absolutely the way to go. They are the EASIEST rodent to breed as long as you follow the rules (kind of like gremlins... LOL) and there smell is NOTHING compared to a normal rat or mouse.