Sucralose and aspertame are both safe sweeteners, despite some of the scare monger websites. I believe that sucralose has an advantage of being more stable than aspertame and can be used for baked goods. Aspertame breaks down quickly with heat. Try storing an aspertame sweetened soda in a hot garage over the summer and you'll find it to be noticeably less sweet than a new one.
When aspertame was first introduced in the US, it was used in a blend with saccharine. This was done to extend the shelf life of the soda as saccharine is also a more stable sweetener than aspertame and would maintain the sweetness of the soda.