If the prototype option had a long-term affect in starship technology or development, I would be rooting for it. However, it appears from QM statements that it would not be so- we are just getting a component for this ship and it is still available next ship without pushing the technology.
So, we should go long-term and go with the +8 to industry. Which adds +1.6 industry per year since it is not being used. So, it really is a +16 Industry for the next 5 years- and then remains on.
@Sayle
If I may make a suggestion for the next investment: perhaps both should be choices that can have a permeant affect? So, perhaps an addition to industry and/or a bonus to prototype rolls? Or have technology development actually be able to push forward technology permanently?